The few Vega-type stars whose dusty debris disks have been resolvedshow this dust to lie in cool Kuiper belt-like rings.However, roughly half of all debris disk candidates exhibit little orno cool dust, since their dust emission peaks at about 25 μm.By analogy with the solar system, these warm disks would lie mid-waybetween the asteroid and Kuiper belt regions in their systems.Are these disks the Kuiper belt-like rings of a truncated planetarysystem?Or do they represent the destruction of massive interplanetaryasteroid/comet belts?Or maybe these systems are in a transitional stage and have yet toevolve into classically cool debris disks?To answer these questions we need to know where the dust lies, andfor that we require the resolving power of mid-IR interferometrywith the VLTI.