Preparations for creation of the air defence forces started in 1932, and by the beginning of Operation Barbarossa, June 1941, there were 13 PVO zones within the military districts.In July 1941, the National Defence Committee took several measures to strengthen the forces guarding Moscow and Leningrad, Yaroslavl and Gorky industrial areas, and strategic bridges across the Volga.[citation needed] The presence of such large forces and their skilful management foiled enemy attempts to inflict massive air strikes.[citation needed] Assaults by the 6th Fighter Aviation Corps inflicted heavy blows, destroying 567 enemy aircraft on the ground.[citation needed] On November 9, 1941, the post of the Commander of the Air Defence Forces was created and Major General Mikhail Gromadin (ru:Громадин, Михаил Степанович) was appointed.In the course of the war, the PVO destroyed 7,313 German aircraft, of which 4,168 and 3,145 were targeted by the IA antiaircraft artillery, machine guns and barrage balloons.[5] The PVO's principal role was to shoot down United States Strategic Air Command bombers if they penetrated Soviet airspace.[7] The PVO gained an important victory on May 1, 1960, when a S-75 Dvina missile downed Gary Powers's U-2, causing the short U-2 crisis of 1960.[8] In February 1971 the 1st Division for Warning Against Missile Attack (1st Division WAMA, 1-я Дивизия предупреждения о ракетном нападении (1-я дПРН)) was formed with HQ in Solnechnegorsk, the 57th Separate Radiotechnical Nod in Olenegorsk, Murmansk Oblast and the 129th Separate Radiotechnical Nod in Skrunda, Latvian SSR.[1] The rest of the country was initially divided into PVO regions covering Belarus, Ukraine, the Baltics and Central Asia.On 1 September 1983 the PVO shot down Korean Air Flight 007 after the civilian airliner had crossed into restricted Soviet airspace and was mistaken for a spy plane.