Introduction
From the deployment of the Terminal High Altitude Area Defense (THAAD) to participating in the US-led Chip 4 alliance, South Korea has often been pressured to choose a side in an intensifying competition between the United States and China (Hosokawa and Hoyama Reference Hosokawa and Hoyama2022; Kim Reference Kim2020; Son Reference Son2022). Whether or not to join the Quadrilateral Security Dialogue, a US-led new grouping for strategic security dialogue—colloquially known as the Quad—has become one of such issues that South Korea must contemplate in recent years (Chung Reference Chung2021; Xue Reference Xue2023). This study investigates how the South Korean public may perceive their country’s decision to join the Quad. While leaders ultimately make foreign policy decisions, domestic politics can play an important role by providing the context within which leaders contemplate such decisions.
Understanding the domestic logic behind South Korean foreign policy decisions can provide valuable insights into the responses of small and middle-power nations to great power competition in Asia. South Korea is not unique in finding its foreign policy space squeezed by both great powers. Countries in Southeast Asia, ranging from the Philippines, a traditional US ally, to Cambodia, which has a long-standing friendly relationship with China, have faced a similar challenge. Individually, these nations are vulnerable to pressures from the two superpowers; however, the collective impact of their decisions has significant implications for how the US–China rivalry unfolds in the region. On one hand, as the US military and economic advantage over China narrows, the support of its Asian allies becomes crucial for the United States in countering the rising power of China (Lee Reference Lee2020). On the other hand, China cannot afford to disregard the potential formation of an anti-China alliance network led by the US in its neighborhood. Consequently, both great powers must also adapt their policies to ensure that small and middle powers do not align with the opposing side.
The core issue that South Korea must consider in navigating its relations with the two superpowers is also akin to that faced by members of the Association of Southeast Asian Nations (ASEAN). Specifically, leaders and analysts in the region have articulated a key trade-off involved in their alignment decision: the United States provides security protection for a country, while China offers economic opportunities. Closely aligning with the United States for security benefits would mean forgoing significant economic opportunities, and vice versa. Recognizing the costs of the trade-off, leaders in Southeast Asia have largely refused to choose a side (CSIS 2022; Straits Times 2022; Sochan Reference Sochan2022). Instead, they have sought to maintain security ties with the United States while improving trade relations with China. Such a strategy, often called hedging, has proven successful and enduring for these countries, in part because it aligns with domestic public preferences (Fang and Li Reference Fang and Li2022; Kuik Reference Kuik2016, Reference Kuik2023; Murphy Reference Murphy2017). However, it remains unclear whether the hedging strategy is applicable to countries outside of Southeast Asia, given their varying security environments, economic conditions, and historical relationships with China and the United States.
In the case of South Korea, its military alliance with the United States has been central to the country’s defense strategies for decades in the face of North Korean nuclear threats. Joining the Quad may further solidify this relationship, alleviating the fear of abandonment that has often arisen in South Korean domestic discourse (Work Reference Work2022a).
At the same time, China has been South Korea’s largest trading partner for the past 20 years (World Bank 2023), and China’s retaliation following South Korea’s initial THAAD deployment in 2016 serves as a reminder of the potential economic repercussions when perceived as aligning with the United States. Furthermore, Beijing wields considerable influence over Pyongyang, not only as its defense treaty ally but also because North Korea heavily relies on China for trade while facing international sanctions (Chung Reference Chung2021; Lee Reference Lee2020; USIP 2019). Beijing has long opposed the nuclearization of the Korean Peninsula; at the same time, it sees a stable North Korea as a partner in balancing against the US alliance network in East Asia (Zhao Reference Zhao2020).
South Korea’s relationships with the United States and China are further complicated by its ties with Japan. The United States, with a regional focus, has long sought to foster closer relationships between its two Northeast Asian allies, South Korea and Japan, in order to facilitate trilateral security cooperation to deter regional rivals. However, unresolved historical grievances related to Korean forced labor and comfort women issues from Japanese colonialism have hindered these efforts. In fact, before the China–South Korea relationship soured due to the deployment of THAAD, China and South Korea collaborated in criticizing and pressuring Japan to confront its past actions (Hanada Reference Hanada2024). Given these intricate security, economic, and historical conditions, how do the perceived security benefits and economic costs of the Quad influence public support for Quad membership? Furthermore, how might individuals’ threat perceptions and their economic self-interest moderate their preferences?
To answer these questions, we designed and implemented an online public opinion survey administered to a nationally representative sample of 2,110 respondents in South Korea in April 2022. The survey was embedded with a randomized experiment where respondents were selectively primed with the security benefits, economic costs, or both, related to joining the US-led grouping. Additionally, the survey included questions that allowed us to examine how the South Korean public’s preferences toward joining the Quad correlated with their threat perceptions, their economic self-interests, and other individual characteristics. Finally, we incorporated open-ended questions in the survey to explore the reasons behind public support for and opposition to joining the Quad.
Two findings emerged from the survey experiment. First, among respondents not subjected to any information priming, nearly half supported joining the Quad. While this support may appear modest when contrasted with the overwhelming approval of the US–ROK alliance in South Korea, but it is considerable given the anticipated economic backlash from China. Second, priming respondents with either the security benefits or potential economic costs associated with Chinese retaliation for joining the Quad did not significantly affect their support levels.
Beyond the experiment, we also explored the effects the respondents’ personal traits, which yielded additional insights. Whereas threat perceptions do not moderate the treatment effects, they are independently and strongly correlated with attitudes toward the Quad: those who felt more threatened by China and North Korea were more likely to support joining the Quad, while those who felt more threatened by Japan were less likely to support it. Furthermore, party affiliation matters. Supporters of the People’s Power Party were more likely to endorse joining the Quad while supporters of the Minjoo Party were less likely to do so. Finally, and somewhat surprisingly, economic self-interest did not play a role in determining support for the Quad, suggesting that when it comes to security-related issues, such as joining the Quad, factors such as threat perceptions or partisanship may dominate considerations over economic self-interest.
Our research contributes to the growing literature on the foreign policy decisions of small and middle powers in Asia in the context of US–China competition. China’s rise has created economic opportunities for other countries in the region, while simultaneously raising concerns about the implications of China’s growing economy for their national interests. The study offers a novel theoretical understanding regarding how the trade-off between security relations with the US and economic relations with China may influence public preferences regarding foreign policy alignment in these countries. Empirically, the study provides a survey design that enables us to test our theoretical argument which can be adapted and implemented in similarly situated countries. Lastly, this study underscores the need for a more nuanced understanding of public opinion in small and middle-power nations on key foreign policy issues. This understanding could have significant implications for peace and stability in Asia and beyond.
The Quad and South Korea’s choices
In the 2018 National Defense Strategy (NDS) of the United States, prepared by the Defense Department for the Trump administration, the reemergence of great power competition was identified as the most important security trend facing the United States (DOD 2018). It was a significant shift in national security priorities, as regional threats had been the focus in previous iterations of the NDS. In addition, while both China and Russia were seen as primary adversaries of the United States, China and the Indo-Pacific region were given priority (DOD 2018; Panda Reference Panda2018). Continuing the shift, in the more recent 2022 NDS, formulated under the Biden administration, China is again designated as the “most consequential competitor” (DOD 2022), and this is despite the ongoing Russian invasion of Ukraine having created crises at a global scale. The two documents suggest that there is broad consensus across US administrations and the two main political parties regarding US foreign policy priority: managing and countering the growing Chinese power.
In addition, both documents identify working with allies and partners in the Indo-Pacific as a key strategy to address the challenge. Against this backdrop, the Quad has become the most visible security architecture embodying the new US defense strategy in the region. In the joint statement of the first-ever Quad summit held in March 2021, the leaders of the group expressed “a shared vision for a free and open Indo-Pacific,” and a desire to “meet challenges to rules-based maritime order in the East and South China seas.” While China was not mentioned in the statement, the forum is widely regarded as aiming to counter the security changes posed by the Indo-Pacific region (Kemp Reference Kemp2021). China took the grouping as such and called it “Asian NATO” (Lin Reference Lin2022; Mohan Reference Mohan2022; Xue Reference Xue2023). There is little question that the evolution of the Quad will be a significant indicator of how US allies are responding to the evolving geopolitical tension in the region (Morford Reference Morford2022).
Unlike NATO, which has existed as a formal military alliance for over 70 years, the nature of the Quad and how it may function as a security partnership are still taking shape. The Quad was first proposed by Japanese Prime Minister Shinzo Abe in 2007 to revive and institutionalize cooperation among four countries who jointly responded to the 2004 Indian Ocean tsunami (Lin Reference Lin2022; Madan Reference Madan2017). However, it was not until 2017 that the revival of the grouping truly took place when President Trump showed an interest in the framework as part of his China policy (Madan Reference Madan2017). Its momentum picked up significantly under the Biden administration with the fifth Quad leaders’ summits held in May 2023, despite the challenge presented by the COVID-19 pandemic in the interim years (The White House 2023).
Even from the early stage, where members convened to discuss the group’s agendas, the idea of Quad Plus, i.e., expanding the membership to include other nations, has been under serious consideration. The first Quad Plus meeting took place in March 2020, when senior representatives from New Zealand, South Korea, and Vietnam were invited to join. A second meeting in the Plus format was held in May of the same year, with South Korea, Israel, and Brazil participating as additional members (Panda Reference Panda2022). Among the potential ‘Plus’ members, South Korea has garnered the most attention (Fitt Reference Fitt2023; Govella, Mohan, and Glaser Reference Govella, Mohan and Glaser2022; Lee and Kang Reference Lee and Kang2023; Li Reference Li2021). In fact, the joint statement issued between the United States and South Korea during President Moon’s visit to Washington in May 2021 includes language stating that the two countries “acknowledge the importance of open, transparent, and inclusive regional multilateralism, including the Quad” (The White House 2021).
South Korea has much to bring to the table. First, it is a long-time military ally of the United States. While the historical focus of the alliance has been on North Korean threats, the Biden administration has sought to expand the scope of the alliance as part of the US Indo-Pacific strategy to contain China (Yoon Reference Yoon2021). Second, South Korea boasts one of the most technologically advanced economies (Shiraishi and Truitt Reference Shiraishi and Truitt2021), particularly in semiconductor manufacturing. The United States has urged Seoul to join its semiconductor export controls to China (Wilkins Reference Wilkins2022). South Korea may also see various benefits in joining the Quad, with a primary goal being to “further strengthen links with the US and gain support for some of its foreign policy goals” (Pardo and Hwang Reference Pardo and Hwang2021). However, such a move will likely result in a deterioration of the relationship between Seoul and Beijing, leading to economic and geopolitical costs for Seoul.
China surpassed the United States to become South Korea’s largest trading partner in 2003 (World Bank 2023) and has since accounted for about one-fourth of South Korea’s exports (Jo, Lee, and Park, Reference Jo, Jeong-gu and Park2023). Some of South Korea’s high-tech industries, such as the semiconductor industry, have been heavily dependent on China for their exports, while also reliant on Chinese supply chains for intermediate goods, causing alarms among the country’s analysts as geopolitical tensions rise (Jung Reference Jung2022; Na Reference Na2022; Park Reference Park2022). The potential economic costs of being perceived as aligning with the United States to undermine China’s interests can be substantial (Global Times 2023).
Between 2016 and 2017, China imposed economic sanctions on some South Korean industries following the country’s deployment of the THAAD missile defense system. This move forced Lotte Group, one of the largest South Korean multinational corporations, to exit the Chinese market, dealing severe blows to South Korean tourism and entertainment industries heavily reliant on the Chinese market (Kim Reference Kim2020; Lim and Ferguson Reference Lim and Ferguson2022; Meick and Salidjanova Reference Meick and Salidjanova2017). The episode continues to cast a long shadow over political discourse in South Korea (Park Reference Park2022). Furthermore, in 2023, South Korea recorded its first trade deficit with China after enjoying an unbroken trade surplus since 1992 when the two countries established diplomatic relations, marking an uncertain period in their bilateral trade relations (Jo, Lee, and Park, Reference Jo, Jeong-gu and Park2023).
The predecessors of the current South Korean president Yoon Suk Yeol had largely adopted a hedging strategy in the great power competition while focusing on the North Korean issue (Chung Reference Chung2021; Heydarian Reference Heydarian2022; Yeo Reference Yeo2022). Similar to Southeast Asian nations, South Korea has engaged in close security cooperation with the US while strengthening economic ties with China (Fang and Li Reference Fang and Li2022; Heydarian Reference Heydarian2017; Kuik Reference Kuik2016; Lee Reference Lee2020; Murphy Reference Murphy2017; Park Reference Park2023). Yoon’s presidency came at a time when this balancing act became more difficult to sustain due to escalating trade and technological conflicts between the United States and China (Choe Reference Choe2022a; Hosokawa and Hoyama Reference Hosokawa and Hoyama2022). Rather than perceiving the narrowing space for hedging as a challenge, Yoon embraced the opportunity to differentiate himself from his predecessors by declaring a clearer pro-US stance (Choe Reference Choe2022a; Yoon Reference Yoon2022). During his presidential campaign, Yoon made two China-related pledges: the additional deployment of THAAD and a move toward membership in the Quad (Kine Reference Kine2022, Yoon Reference Yoon2022). Since taking office, Yoon has improved relations with Japan by making concessions on the compensation schemes of Korean forced labor victims of the Japanese colonial era; this reconciliation, in turn, made possible a US–Japan–South Korea summit at Camp David, the first-of-its-kind trilateral meeting (Kim Reference Kim2023; Lee Reference Lee2023). Despite these big shifts in foreign policy, it is worth noting that Yoon has also delayed the further deployment of THAAD and has helped Korean semiconductor manufacturers secure a waiver from US government export controls on their products to China (Borowiec and Okumura Reference Borowiec and Okumura2023; Grossman Reference Grossman2023).
The durability of South Korea’s foreign policy redirection remains uncertain. Yoon won the presidency in “South Korea’s tightest race since it began holding free presidential elections in 1987” (Choe Reference Choe2022b) and has experienced a persistently low approval rating below 40 percent. With a weak domestic political foundation, Yoon may need to be particularly attentive to public opinion on Seoul’s relations with both Pyongyang and Beijing, where there is a high degree of domestic polarization (Chung Reference Chung2023; Kim Reference Yoo-chul2022; Kim Reference Kim2023). Securing broad domestic public support on matters such as joining the Quad is crucial to prevent policy reversals after his tenure (Cha et al. Reference Cha, Johnstone, Kim and Szechenyi2023; Kim Reference Kim2023; Lee Reference Lee2023; Lee and Kang Reference Lee and Kang2023; Yeo Reference Yeo2023).
Gauging public support for the Quad
Most existing public opinion surveys about foreign policy issues in South Korea, such as the Pew Global Attitudes Survey and the Genron NPO polls, focus on broad questions such as the public’s perceptions of China and the United States, South Korea’s bilateral relations with the two countries, and opinions on issues of peace and conflict in Northeast Asia (Kudo Reference Kudo2016; Silver, Huang, and Clancy, Reference Silver, Huang and Clancy2022). However, there have been a few recent public opinion studies conducted by South Korean think tanks that included a question about South Korea joining the Quad (Lee et al. Reference Lee, Min, Yoon and Koo2021; Kim, Kang, and Ham Reference Kim, Kang and Ham2022; Lee and Kang Reference Lee and Kang2023). Each survey presented the nature of the Quad somewhat differently to the respondents, ranging from describing it simply as a cooperative framework among the US, Japan, Australia, and India to a multilateral security framework of these countries to counter China’s rise. The level of support for joining the Quad found in the surveys varied greatly, ranging from around 30 percent to above 80 percent (Lee and Kang Reference Lee and Kang2023).
There are several drawbacks to how the question about the Quad was asked in these surveys. First, because the question about the Quad was embedded in lengthy surveys that focused on other issues, such as reunification and policy toward Norther Korea (Lee et al. Reference Lee, Min, Yoon and Koo2021) or the ROK–US alliance (Kim, Kang, and Ham Reference Kim, Kang and Ham2022), the results were likely influenced by the effects of the proceeding questions. Second, none of the Quad questions in the surveys explicitly stated the potential trade-off between the security and economic interests involved in the decision to their respondents. Finally, the choices given to answer the questions were not comparable across the surveys, with some allowing respondents to express their uncertainty, while others did not provide a “don’t know” option (P. Lee and Kang Reference Lee and Kang2023). These factors might have either depressed or inflated the degree of support.Footnote 1
Our survey design focuses on the Quad issue with no other leading questions. More importantly, to better identify whether and how South Koreans weigh the security and economic trade-off in joining the Quad, we used a survey experiment that randomly assigns respondents to a control condition in which they read general information about the Quad and three treatment conditions where they are explicitly reminded of the (1) security benefits; (2) economic costs from China’s retaliation; or (3) both the security benefits and economic costs from China’s retaliation if South Korea joins the Quad. The first two hypotheses following these treatments are straightforward:Footnote 2
H1: Those reminded of the security benefits of the Quad are more likely to support South Korea joining the Quad.
H2: Those reminded of the potential economic sanctions from Beijing are less likely to support South Korea joining the Quad.
For the third treatment condition, we expect that the effects of being reminded of both the security benefits and economic costs will depend on how individuals perceive the threat environment surrounding South Korea and their economic self-interests related to South Korea’s trade relations with China. Specifically, we consider a spectrum of individual circumstances. On one end are those who perceive China as a significant security threat; among them, some are economically reliant on China for their jobs and livelihoods, while others are not. On the opposite end are individuals who do not view China as a security threat, yet their economic conditions vary similarly—some depend on trade with China for their economic well-being, and others do not.
When these individuals are primed with both the security benefits of joining the Quad and the economic costs resulting from Chinese sanctions in response to South Korea’s Quad membership, we anticipate varying responses. Specifically, we expect those who perceive China to be threatening while not being economically dependent on China to be more likely to support South Korea’s Quad membership. Conversely, those who do not see China as a threat and are economically dependent may be more likely to oppose South Korea’s Quad membership. The anticipated responses of those who perceive China as a security threat but are also economically dependent on China, as well as those who neither perceive a threat nor economically dependent on China, remain ambiguous. Therefore, our analysis will focus on the two groups at the ends of the spectrum, which provide clear theoretical contrasts, leading to the following:
H3a: When reminded of both the security benefits and economic costs, the group that perceives China as a security threat and is less economically dependent on China will be more likely to support South Korea joining the Quad than the same group in the control condition.
H3b: When reminded of both the security benefits and economic costs, the group that perceives China less as a security threat and is more economically dependent on China will be less likely to support South Korea joining the Quad than the same group in the control condition.
4. Survey design
We designed and administered our survey between April and June 2022 through dataSpring, a survey firm in South Korea. The company maintains an online panel of respondents in South Korea who take surveys in exchange for small cash payments. Respondents for the sample were drawn randomly from the online panel using a quota sampling strategy that targets pre-specified proportions of gender, age group, and geographic location, based on the latest census. Each of the solicited respondents was provided a link by the firm that redirects them to the survey as well as the consent information. Upon completing the survey, they were redirected back to the company’s website to claim their reward.
The survey experiment proceeds as follows. First, each respondent read a short paragraph on the background of the Quad:
The Quadrilateral Security Dialogue, also known as the Quad, is an organization between the United States, Japan, Australia, and India that is widely viewed as intending to counter China’s growing economic and military power. China, which is the number one trading partner of South Korea, has criticized the Quad for inciting discord among countries in Asia.
They further read that “South Korea has been invited to join the Quad.”
Next, respondents are randomly assigned either the control group or one of the three treatment groups, in which they received an additional message priming them with either security benefits or economic costs, or both, as detailed below:
Security Benefits: The United States maintains that South Korea’s membership would further strengthen the alliance relationship between South Korea and the United States.
Economic Costs: China has warned that if South Korea joins the Quad, it will retaliate with strong economic sanctions.
Combined: The US maintains that South Korea’s membership would further strengthen the alliance relationship between South Korea and the United States. China has warned that if South Korea joins the Quad, it will retaliate with strong economic sanctions.
Finally, respondents were asked, “How much do you agree or disagree with the idea that South Korea should join the Quad?” The answers are on a five-point scale from “strongly disagree” to “strongly agree” and are our main outcome measures.
To understand the logic behind the answers beyond the key trade-off, we introduced a post-treatment open-ended question for a portion of our correspondents: “Please write a few words about why you either agree or disagree with the idea that South Korea should join the Quad.” The survey also included standard demographic and attitudinal questions to measure the socioeconomic status of the respondents and their degree of nationalism.Footnote 3
Findings
Between April 13 and July 7, a total of 2,110 respondents completed our survey. To ensure the integrity of our data, we excluded participants who completed the survey in less than three minutes. This decision was based on our assessment that a thorough engagement with the survey questions requires a minimum amount of time, determined by the average duration most respondents took to provide thoughtful and considered responses. This resulted in a final sample size of 1,890. Quota sampling ensured our sample was representative with respect to key demographic characteristics of age, gender, and geographic distribution. The average age of the respondents was 44.5 years old, with 51% of the sample being male, and around 67% had college degrees. 23.8% of the respondents had a monthly income of less than 3 million won, 30.1% had an income of over 6 million won, and 46.1% of the respondents fell into the middle-income group. These figures are rather similar to the 2021 census population.Footnote 4
Figure 1 displays the overall distribution of the responses to the question: “How much do you agree or disagree with the idea that South Korea should join the Quad?” in the control group—those respondents who were not primed with any additional information. The median response was neither agree nor disagree, with 33% in the group. Slightly more (34.7%) answered somewhat agree and only 13.8% strongly supported the idea. Combined, less than half of respondents (48.5%) supported South Korea joining the Quad.
Level of Support for Joining the Quad.
Note: The distribution is calculated for the control group (N = 465).
The interpretation of this figure can vary depending on the context used to set expectations regarding support for the Quad. On one hand, the level of support appears tepid, especially when compared to the consistently high public endorsement of the US–ROK alliance, which exceeds 90 percent according to a recent study (Kim, Kang, and Ham Reference Kim, Kang and Ham2022). On the other hand, considering the widespread awareness of potential economic repercussions from China in response to South Korea joining the Quad, the level of support seems quite significant.
Treatment effects
How did the information priming affect respondent support for joining the Quad? To answer this question and test our hypotheses, we estimated the average treatment effects (ATEs) by comparing the means of the outcome variable across the control and two treatment conditions in a regression model. For ease of interpretation, the responses to the question of whether South Korea should join the Quad were rescaled as binary, with ‘1’ indicating agreement with joining the Quad and ‘0’ disagreement. The results are presented in Figure 2. As predicted by H1 and H2, reminding people of security benefits increased their support for joining the Quad, while reminding them of possible economic costs imposed by China led to decreased support. However, although the treatment effects of both security benefits and economic costs were in the expected direction, neither reached statistical significance.Footnote 5 We also did not find any heterogeneous treatment effects by individuals’ party ID, political ideology, or their prior knowledge of the Quad. While these variables influenced respondents’ baseline level of support for the Quad as we will show in Table 1, they did not lead to different treatment effects for each subgroup.
Average Treatment Effect of Security and Economic Primes.
Note: Point estimates based on a linear probability model (LPM) represent treatment effects relative to the control condition, with positive numbers indicating more support for South Korea joining the Quad.Footnote 6 Inner confidence intervals indicate 90 percent robust confidence intervals and outer confidence intervals at 95 percent. Control (n=465); Security benefits (n=451); Economic costs (n=498). Full estimation results are available in the online appendix.
Individual determinants of support for the Quad
Note: Baseline category for Party Identity is Independents (41% of the sample). Ideology and Nationalism are on a 5-point scale, with higher values indicating more conservative attitudes and stronger levels of nationalism. See the survey design in the online appendix for questions used to measure these values.
Robust SEs.
*p<0.05; **p<0.01.
Next, we analyzed how the combined reminder of security benefits and economic costs influenced respondents’ support for the Quad, taking into consideration their individual characteristics, with the most important ones being their threat perceptions and economic dependence on China (H3a and H3b). The former pertains to the security benefits of joining the Quad, while the latter relates to the potential economic costs resulting from China’s retaliation if South Korea were to join the Quad. We asked several pre-treatment questions to measure these two variables, which we will describe below.
For the perceived security benefits from joining the Quad, we asked respondents about their perceptions of China, Japan, and North Korea as security threats. The perceptions were measured using their responses to “In your opinion, how threatening is China/Japan/North Korea to South Korean national security?” on a seven-point scale. The order in which the three countries were presented was randomized. For each country, we coded respondents as having “low” threat perception for those who answered, “neither threatening nor unthreatening,” “somewhat unthreatening,” “unthreatening,” or “very unthreatening.” In the case of China, in total, 83 percent of the respondents answered that China was at least “somewhat threatening,” with 36.8 percent and 24.2 percent each answering “threatening” or “very threatening.”
The survey also included several questions aimed at assessing potential economic costs to individuals that could result from Chinese retaliation due to South Korea joining the Quad. First, respondents were asked to specify their employment sector. We categorized those working in the “Arts and Entertainment,” “Accommodation,” and “Transportation” sectors as more dependent on China for their jobs, given their vulnerability to Chinese economic sanctions during the THAAD deployment in 2016 (Lim and Ferguson Reference Lim and Ferguson2022). Respondents were also asked whether their jobs involved dealings with Chinese businesses and customers, either directly or indirectly. Those who answered “yes” were further inquired about the frequency of their interactions with Chinese entities, with response options ranging from “very frequently” to “very rarely.” Lastly, to gauge respondents’ reliance on Chinese exports for their daily needs, we asked them to provide an estimation of the proportion of products and goods they use that are made in China, with choices including “almost none,” “less than 25%,” “25%—50%,” and “greater than 50%.”
In terms of economic dependency, 6.5 percent of our sample worked in industries most vulnerable to China. 18.6 percent of our respondents’ jobs involved dealing with Chinese businesses or customers, either directly or indirectly, and 14 percent stated that over 50 percent of their daily products and goods were made in China. We used information from these three questions to create a composite measure of economic dependency on China (China Dependent), ranging from 0 to 1, with 0 indicating low reliance on China and 1 indicating high reliance on China. The variable has a median value of 0.22 and an average of 0.25.Footnote 7
The results for H3a and H3b are reported In Figure 3. We categorized individuals as feeling threatened by China if they responded with “somewhat threatened” or higher, and as having high economic dependency on China if they scored above the median value (0.22) on the combined China Dependent variable. We found that the treatment effects trended in the expected direction. Specifically, when respondents were simultaneously reminded of the security benefits and economic costs, those concerned about China as a security threat but not economically dependent on China (comprising 56 percent of the full sample) were 2.1 percent more likely to support joining the Quad compared to the control group (increased from 51.2 percent to 53.3 percent). In contrast, respondents not concerned about China as a security threat but economically dependent on China (comprising 6 percent of the full sample) were 7.9 percent less likely to support joining the Quad when reminded of both the security benefits and economic costs compared to the control group (decreased from 31.4 percent to 23.9 percent).
Conditional Average Treatment Effects by Individual’s Threat Perception & Economic Dependence.
Note: Point estimates based on LPM represent the treatment effects of receiving the combined condition relative to the control condition, with positive numbers indicating more support for South Korea joining the Quad. Inner confidence intervals indicate 90 percent robust confidence intervals and outer confidence intervals at 95 percent. Threatened & Not dependent (n= 501); Not Threatened & Dependent (n= 52).
While the direction of the treatment effects aligns with our expectations, they did not achieve statistical significance at the conventional level. We believe this result could be attributed to two reasons. One is that the sample sizes may not have been large enough to detect small treatment effects. Another, and perhaps more significant reason, is that respondents might have been exposed to similar information in our treatments prior to taking the survey, diluting the difference between the treatment and control groups. In other words, our treatments did not provide additional information to our respondents. Substantial evidence supports this second point. We found that 77.7 percent of our respondents had already been either paying close attention to the Quad issue or had at least heard of it. In addition, the security–economic trade-off of aligning with the United States over China appeared to be deeply ingrained among many respondents, perhaps due to previous experience with the THAAD crisis, judging from the answers to our open-ended question, which we will discuss below in more detail.
The effects of individual characteristics on the support for Quad
In addition to the treatment effects, we also examined individuals’ characteristics that may provide cues to their attitudes toward joining the Quad, using the battery of sociodemographic and attitudinal questions included in our survey. Table 1 presents the results from an LPM with robust standard errors. We highlight three main findings. First, we found that people’s threat perceptions toward China, North Korea, and Japan strongly predict their attitudes toward the Quad. Those who felt more threatened by China and North Korea were more likely to support joining the Quad. Conversely, those who felt more threatened by Japan were less likely to support joining a coalition where Japan was already a member. The effects were also substantively large. For example, someone who felt very threatened by China was 46.8 percent more likely to support joining the Quad compared to someone who felt very unthreatened by China.
Second, partisanship emerged as a strong predictor even after controlling for the respondent’s level of threat perceptions and their other individual characteristics. Compared to the baseline category (Independents), supporters of the conservative People’s Power Party (PPP)—the party of the incumbent President Yoon Suk-yeol—were 15.9 percent more likely to support joining the Quad, while supporters of the Minjoo Party, which is the more liberal and main rival party of PPP, were 6 percent less likely to support the US-led grouping. The fact that party identification remained a powerful determinant even after controlling for other variables reflects how foreign relations with China and the United States are heavily politicized in South Korean domestic politics (Moon and Boo Reference Moon and Seung-chan2017).
Third, we found that an individual’s level of economic dependency on China, such as being employed in jobs that deal with China, affiliation with industries vulnerable to Chinese sanctions, or heavy use of Chinese manufactured goods (China Dependent), did not play a role in determining support for the Quad. The variable is statistically insignificant when tested against the dependent variable without any additional controls, or when each component of the China Dependent variable is tested separately. This is surprising given that the conventional wisdom in the existing political economy literature is that economic self-interests influence individuals’ trade policy preferences (e.g., Scheve and Slaughter Reference Scheve and Slaughter2001). Our findings suggest that when it comes to security-related issues, such as joining the Quad, factors such as threat perceptions or partisanship may dominate considerations of economic self-interests.
Table 1 also shows that the respondent’s gender and nationalism are significant predictors of their support for the Quad. Male citizens indicated a higher willingness to support the US-led coalition. While the exact reason is beyond the scope of this study, it may be the case that males are more comfortable with aggressive policies that revise the status quo (Eichenberg Reference Eichenberg2016). Furthermore, individuals who indicated higher levels of pride and attachment to the Korean nation (nationalism) were more likely to support joining the Quad.
Open-ended Answers
The open-ended question allowed us to delve deeper into the thought processes behind individuals’ responses to the Quad question. A subset of our sample (n=755, 36%) responded by writing a couple of sentences on why they chose to either agree, disagree, or neither agree nor disagree with joining the Quad. As we sifted through the responses, we noticed several interesting patterns.
First, considerations about China played the biggest role in determining whether individuals chose to support or oppose across all treatment conditions, even among those who were only reminded of US security guarantees (Figure 4). This, to some extent, supports our conjecture that our priming treatments might have been too weak because the informational environment in which our respondents reside was already saturated with Quad-relevant discussions. Specifically, respondents who supported joining the Quad did so because they viewed China as a security threat, while respondents who opposed joining the Quad did so because they were concerned it would upset China. In fact, the single most mentioned word was “China (중국)”—292 times—almost six times more than the US (50). Their concerns regarding China–South Korea relations were also often expressed in the context of potential Chinese economic retaliation, with the word “economy” being one of the five most frequently mentioned substantive words in the open answers, appearing 53 times. This suggests that, although support for the ROK–US alliance remains strong, South Koreans are mindful of the economic implications of their relationship with China. Consequently, this awareness may act as a constraint on their foreign policy preferences. North Korea and Japan did not play a big role, being mentioned only 30 and 15 times, respectively.
Frequency of words in open-ended question.
Second, “protection of Korean sovereignty” was one of the most common rationales given by both supporters and opposers of the Quad. For example, the United States’ offer to strengthen the alliance ties between the two countries was interpreted by some people as disrespectful of Korean agency, as evidenced by answers such as “We don’t always have to do what the US wants,” “South Korea is not a US vassal state,” and “South Korea should do what is best for its own interests, not for US interests.” Again, while the South Korean public generally holds highly positive views of the United States and desires close bilateral relations, there are enduring concerns about their country’s sovereignty in relation to the United States. Similarly, China’s threats of economic retaliation also backfired on many respondents, who thought “China is bullying us again” and pushed them toward supporting the Quad despite the economic costs. This concern for sovereignty may be yet another reason why the treatment conditions were not effective in changing people’s preferences as we hypothesized: the (dis)incentives provided by either the US or China in our survey design, which mimics real-world scenarios, were counterproductive for some respondents as they interpreted the two countries as interfering with Korean sovereignty.
Lastly, the open-ended responses indicate that for some individuals, there are other aspects of joining the Quad that are appealing, such as raising South Korea’s status in the world by becoming a part of an alliance of democratic states. About 8 percent of the individuals who expressed support for the Quad provided answers like “to raise South Korea’s status in the world” or “to tell the world that South Korea is part of advanced/democratic countries.” This aligns with the official rhetoric of the South Korean government, which has echoed the Biden administration’s characterization of the Quad as a grouping of democracies. Expectations of such additional benefits, apart from the security benefits or economic costs of the Quad itself, may also be a reason why the treatment conditions were not as effective as hypothesized and could be worth exploring in the future.
Conclusion
The intense competition between China and the United States for global influence has presented many countries with a foreign policy dilemma: they are often expected to declare their positions on an issue that could be interpreted as aligning with one superpower against the other. This pressure to take sides has been most pronounced in Asia, where many countries are traditional allies of the United States but have also become deeply intertwined with China economically over the last twenty years. South Korea epitomizes this dilemma more than any other nation, with its military alliance with the United States being one of the longest and strongest in the region, while its economic dependence on China is extensive.
Lurking in the background are also tensions on the Korean peninsula as a result of North Korean nuclear programs and weapons tests. In addition, new uncertainty has arisen since the outbreak of the Ukraine war, with a deepening relationship between Pyongyang and Moscow even as South Korea aligns more closely with the United States regarding the war. These developments require at least some degree of cooperation between the two superpowers to manage due to their shared interest in a stable Korean peninsula (Yonhap 2024). Therefore, the space for South Korea to navigate this triangular relationship is narrow, and yet its alignment decision will have significant implications, both substantively and symbolically, for South Korea as well as for US–China competition more broadly.
Domestic politics introduces additional layers of complexities to South Korea’s foreign policies. With a single five-year presidential term free from re-election concerns, South Korean presidents enjoy considerable power in shaping foreign policies (Lee Reference Lee2023). However, these policies may be subject to reversals without sufficient public support when governments change, as exemplified by the 2015 Japan–South Korea Comfort Women Agreement, signed between President Park Geun-hye and Japanese Prime Minister Shinzo Abe, but suspended by the subsequent administration. Furthermore, the South Korean public has a history of holding politicians to account, including successful protests that led to the removal of President Park Geun-hyu. Given the unprecedented narrow margin of victory by which the current President Yoon Suk Yeol came into office and his persistently low approval ratings, the public’s perception of key foreign policy decisions will likely influence his administration’s considerations.
Bearing the significance of domestic politics in mind, this research investigates South Korean public attitudes toward the prospect of joining the Quad, a decision that is likely to be widely interpreted as choosing the side of the United States over China. We found that close to a majority (48.5 percent) of respondents not receiving additional information priming support joining the Quad. However, our three experimental treatments—highlighting the security benefits of joining the Quad through closer alignment with the United States, the potential economic costs from Chinese retaliation for joining the Quad, and the combination of both—did not significantly sway support for joining the Quad. Substantial evidence suggests that the seeming indifference to our treatments may stem from the respondents’ pre-existing awareness of the security–economic trade-offs associated with Quad membership.
When examining individual characteristics that may influence their attitudes toward joining the Quad, we identified threat perceptions and party affiliation as the two strongest predictors of their support for the Quad. Specifically, those feeling more threatened by China and North Korea showed a greater inclination to endorse Quad membership, as were those who supported President Yoon’s party. Conversely, those viewing Japan as a threat were less likely to support joining the Quad, possibly due to Japan already being a member of the grouping. Intriguingly, an individual’s level of economic dependency on China did not play a role in determining support for the Quad. These findings indicate that individuals’ beliefs about South Korea’s security environment and their party loyalty play a bigger role than economic self-interest in shaping preferences on security-related issues, such as joining the Quad.
Additional insights emerged from the open-ended responses: “protection of Korean sovereignty” was the most common reason given by both supporters and opposers of the Quad. A largely overlooked component of nationalism in Asia, including South Korea, is a strong preference for foreign policy independence stemming from historical experiences of colonial subjugation and subsequent loss of sovereignty and decision-making autonomy (Lee Reference Lee2007). This pattern can be observed in regional leaders’ reluctance to take sides in the great power competition and the prevalence of a hedging strategy in Southeast Asia. Such sentiments also seem to resonate with South Korean respondents. Many respondents in our survey might have viewed the suggestion of either an even closer security alignment with the US or the threat of economic sanctions by China as an infringement on Korean sovereignty. This suggests that South Korea may be less likely to fully embrace US hardline policies towards China than perhaps initially anticipated in Washington following Yoon’s election (Fulco Reference Fulco2023; Grossman Reference Grossman2023). Despite moving closer to the United States compared to his predecessor, Yoon operates within enduring trends in South Korean foreign policy, characterized by a widespread preference for a balancing act, safeguarding sovereignty amidst the pressures exerted by competing great powers.
Supplementary Material
The supplementary material for this article can be found at http://doi.org/10.1017/jea.2024.18.
Acknowledgments
We thank the participants of the workshop “South Korea’s Role in the Era of a U.S.-China Rivalry” held at the University of Tennessee.
Financial Support
This work was supported by the Social Sciences and Humanities Research Council of Canada under Grant 435–2018–0396 and Rice University.
Competing interests
The authors declare none.
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