The political tendencies in Numsa dominated different areas of union life. Politically, the charterists dominated, while in the organisational terrain the workerists held sway. This duality was highlighted in the union's approach to disinvestment, where the charterist position prevailed, while the workerists managed the practical fallout. But the principle of isolating the apartheid regime by calling for the withdrawal of foreign interests was supported by all tendencies.

Between 1985 and 1986, the international campaign for sanctions and disinvestment, endorsed by the ANC and Sactu gathered momentum. Fosatu was not entirely sympathetic to this call, but was concerned not to align itself with employers and conservative homeland leaders such as Buthelezi. It adopted a typically flexible and nuanced position.

In a policy statement, Fosatu identified three issues which would make international pressure effective. It related disinvestment to the building of worker organisation through the international solidarity of labour which could exert pressure on multinational companies in South Africa, and it also supported the disinvestment campaign in such measures as terminating borrowing facilities to the government. On existing foreign investment, Fosatu was more ambivalent, as the withdrawal of foreign companies meant ‘sacrificing jobs now for liberation later’. Fosatu's decision to support sanctions conflicted with its role of protecting members against job losses and it argued that South African workers had built these companies into profitable concerns through their labour so these assets were a part of the country's wealth so it could not accept the logic of sacrificing jobs or wealth-generating assets.

At its launching congress in 1985, Cosatu decided to support the disinvestment campaign but, influenced by the Fosatu position, it attached conditions and declared ‘that the social wealth of South Africa remains the property of the people of South Africa for the benefit of all’. Its 1987 congress urged companies to give unions adequate notice of their intention to disinvest and to negotiate the terms of departure. Implementation of the policy, however, remained vague, as it ‘dumped the problem back in the laps of twelve affiliate unions’. Numsa, in managing both the political and economic implications, was cautious and avoided a campaign which actively called for disinvestment; its demands were to do with companies’ manner of withdrawal.