established in 1975, to be celebrated on April 11. In 1980 this was changed to the second Sunday of April. It is still celebrated in the Russian Federation even after the 1998 merger of the Air Defence Forces with the Air Force. The unofficial motto of the PVO is 'Сами не летаем – другим не дадим'('Sami ne letaem – drugim ne dadim'), which can be translated as "Don't fly – don't let others" / "If we can't fly – we won't let anyone else either". Commanders-in-Chief, Air Defence Forces Marshal of the Soviet Union Leonid Govorov – 1954–1955 Marshal of the Soviet Union Sergey Biryuzov – 1955–1962 Marshal of Aviation Vladimir Sudets – 1962–1966 Marshal of the Soviet Union Pavel Batitsky – 1966–1978 Chief Marshal of Aviation Alexander Koldunov – 1978 – May 1987 General of the Army Ivan Тret'yak – 31 May 1987 – 24 August 1991 General of the Army Viktor Prudnikov – September 1991 – December 1997 Colonel-General Viktor Sinitsin – December 1997 – Feb 1998 The post was then disestablished with the merger of the PVO and VVS in 1998. Structure The PVO structure during the Cold War and in Russia until 1998 consisted of three specialized branches: the Radiotechnical Troops (радиотехнические войска), Surface-to-Air Missile Troops (зенитно-ракетные войска), and Fighter Aviation (истребительная авиация; istrebitel'naya aviatsiya; IA-PVO). Armies, corps, and divisions of the PVO were made up of units from all three branches. Moscow Air Defence District (now the Russian Special Purpose Command) 2nd Air Defence Army (Belorussian Military District) 4th Independent Air Defence Army (HQ Sverdlovsk) 5th Air Defence Corps 19th Air Defence Corps 20th Air Defence Corps (Perm, Perm Oblast) 763rd Fighter Aviation Regiment 764th Fighter Aviation Regiment 765th Fighter Aviation Regiment PVO 6th Independent Air Defence Army (Leningrad Military District) 27th Air Defence Corps, Riga, 54th Air Defence Corps 14th Air Defence Division, Tallinn 8th Air Defence Army (HQ Kiev) 49th Air Defence Corps 60th Air Defence Corps 10th Independent Air Defence Army (HQ Arkhangelsk) 11th Red Banner Army of the PVO (Far East Military District) 8th Air Defence Corps 23rd Air Defence Corps 6th Air Defence Division 24th Air Defence Division and 29th Divisions of the PVO 12th Independent Air Defence Army (HQ Tashkent) 24th and 37th Corps of the PVO 14th Independent Air Defence Army (Siberian Military District) 38th Air Defence Corps 39th Air Defence Corps (Irkutsk) (:ru:Мукденское соединение ПВО) 50th Air