MOSCOW, Sept. 30 (UPI) -- Russia's Tupolev Tu-160 White Swan bombers are back from Venezuela. The overseas visit by the most powerful strike aircraft of Russia has created a new surge of interest in these planes, which make up the core of Russian strategic aviation.

The supersonic missile-carrying Tu-160 bomber -- NATO designation Blackjack -- was developed in the early 1970s, when it became clear that subsonic 3M and Tupolev Tu-95 bombers, which did not yet carry long-range cruise missiles, were unable to penetrate the air defenses of the North Atlantic Treaty Organization in a conflict. The maiden flight of the new plane took place at the end of 1981.

From the outset, the Tupolev Tu-160 was designed as a missile-carrying bomber, which, with its high-altitude performance, would be less vulnerable when breaking through NATO's air defenses. Its serial production began in 1984, and in 1987 the first units joined the Russian air force. By 1991 the Soviet Union had 19 Tupolev Tu-160 strategic bombers in service, which belonged to the 184th Heavy Bomber Regiment at Priluki, Ukraine.

Following the collapse of the Soviet Union at the end of 1991, Russia's new leadership decided to discontinue the production of Tupolev Tu-160s and Tupolev Tu-95MSs -- NATO designation Bear -- and also to stop regular flights by strategic aviation outside Russia's airspace. With completion of nearly ready aircraft, Russia's air force was found to have only six "White Swans," as pilots dubbed the Tupolev Tu-160. A few others were used as flying laboratories for all sorts of tests.

Ukraine, meanwhile, decided to disband its force of strategic bombers. It resolved to return eight Tupolev Tu-160 Blackjacks and three Tupolev Tu-95 Bears to Russia in exchange for gas debt.