In 1962, in response to advances in Soviet Union surface-to-air missile (SAM) technology, the V-force fleet including the Valiant changed from high-level flying to flying at low-level to avoid SAM attacks that they would have received if they were flying at high altitudes. In 1964 it was found that Valiants showed fatigue and crystalline corrosion in wing rear spar attachment forgings. In late 1964 a repair programme was underway, but a change of Government led to the new Minister of Defence Denis Healey deciding that the Valiant should be retired from service, and this happened in early 1965. The Victor and Vulcan V-bombers remained in service until the 1980s.