Russian President Vladimir Putin has ordered the resumption of manufacture of supersonic Tu-160 strategic bombers but in a modernised form, called the Tu-160M, state-run newspaper Rossiyskaya Gazeta reported on Friday.Commander of the Russian air force Gen. Viktor Bondarev said Russia's air force would purchase at least 50 Tu-160M strategic bombers.The Tu-160 -- "Blackjack" according to NATO -- is a variable-geometry-wing aircraft designed by Tupolev that entered service in 1987, four years before the collapse of the Soviet Union.The aircraft are the world's most powerful heavy bombers, as they can carry up to 40 tonnes of bombs and missiles.The aircraft is manned by a four-member crew and can cover distances of up to 14,600 km at an altitude of 59,000 feet, without refueling, and can reach speeds up to 2,230 km per hour.According to Rossiyskaya Gazeta, the Tu-160M will be manufactured in the city of Kazan and will be equipped with highly advanced on-board systems and armed with long-range cruise missiles (up to 10,000 km) capable of carrying nuclear warheads.