The SR-71, with its impressive and unorthodox appearance, is the younger sister of the U-2 with the Important difference that it is built to perform its duties at MACH 3.5. U.S. STRATEGIC AIR COMMAND has stated that the BLACKBIRD is still holding the world’s speed record. It can cross the United States in less than an.hour. The SR-71s have been used in all the countries of the world, flying over Cuba, China, Vietnam, Middle East etc in times of international tension or of local conflicts, even operating in Okinawa, Thailand and the Philippines. It is today’s most sophisticated spy aircraft.