The specter of bombardment satellites and the reality of ballistic missiles stimulated the Soviet Union to explore defensive space weapons. The Soviet Union first tested the Polyot interceptor in 1963 and successfully tested an orbital anti-satellite (ASAT) weapon in 1968 According to some accounts, Sergei Korolev started some work on the concept in 1956 at his OKB-1, while others attribute the work to Vladimir Chelomei's OKB-52 around 1959. What is certain is that at the beginning of April 1960, Nikita Khrushchev held a meeting at his summer residence in Crimea, discussing an array of defence industry issues. Here, Chelomei outlined his rocket and spacecraft program, and received a go-ahead to start development of the UR-200 rocket, one of its many roles being the launcher for his anti-satellite project. The decision to start work on the weapon, as part of the Istrebitel Sputnikov (IS) (lit. "destroyer of satellites") program, was made in March 1961.