The accidental overestimate by the United States of Soviet missile strengths prior to 1962 was corrected by photographic reconnaissance conducted by CORONA satellites, which demonstrated that in 1960 the Soviets possessed only four of the SS-6 Intercontinental Ballistic Missile (ICBM) designated Sapwood by NATO. The exaggeration, deliberately propagated by Nikita Khrushchev, suggested a comparative Soviet advantage over the Americans in ICBMs, a political imbalance that was to become known as the “missile gap” until it was disproved by aircraft reconnaissance and satellite imagery, backed by information from Oleg Penkovsky.