The success of Korabl-Sputnik 2 gave the designers confidence to put forward a plan leading to a human spaceflight. A document regarding a plan for the Vostok programme, dated September 10, 1960, and declassified in 1991, was sent to the Central Committee of the Communist Party, and approved by Premier Nikita Khrushchev. This document had been signed by the top leaders in the Soviet defence industry at the time, the most senior being Deputy Chairman Dmitriy Ustinov; this indicated the elevated importance of the document. The plan called for one or two more "Vostok 1K" flights, followed by two uncrewed "Vostok 3K" flights, followed by a crewed flight in December 1960.