The TOPAZ International Program (TIP) was the final name given to a series of projects to purchase for testing in the United States the TOPAZ-II, a space-based nuclear reactor of a type that had been more fully developed in the Soviet Union than in the United States. The TOPAZ-II represented the more than twenty years of the Soviet space program’s experience with nuclear thermionic power system technology, which matured during the period from 1969 to 1990. In the changing political situation associated with the dissolution of the Soviet Union, it became possible for the United States to not just purchase the system, but also to employ Russian scientists, engineers, and testing facilities to verify its reliability. The TIP presented the only opportunity for Russian scientists and engineers to continue the development of thermionic space nuclear power systems for civil (non-defense) applications, as funding for these efforts in the USSR had been cut off. The TIP became the first prominent example of international cooperation between Russia and the United States in a formerly highly classified area of technology following the collapse of the Soviet Union.