aircraft, plus trainers which include 8 L-39C, and helicopters, mainly Mil Mi-8, Mil Mi-17, and Mil Mi-24 Hind. Raúl Castro ordered in 2010 that all MiG-29 pilots had to have full training, they now have from 200–250 hours of flight annually together with real dogfight training and exercises. Up to 20 MiG-23 units also have this kind of training but the other 16 MiG-23 units spend more time in simulators than real flight. MiG-21 units have limited time in these training exercises and spend more time in simulators and maintain their skills flying with Aerogaviota, the commercial brand of the air force. Revolutionary Navy In 1988, the Cuban Navy boasted 12,000 men, three submarines, two modern guided-missile frigates, one intelligence vessel, and a large number of patrol craft and minesweepers. However, most of the Soviet-made vessels have been decommissioned or sunk to make reefs. By 2007, the Cuban Navy was assessed as being 3,000 strong (including up to 550+ Navy Infantry) by the IISS with six Osa-II missile boats and one . The Cuban Navy also includes a small marine battalion called the Desembarco de Granma. It once numbered 550 men, though its present size is not known. After the old Soviet submarines were put out of service, Cuba searched for help from North Korea's experience in midget submarines. North Korean defectors claimed to have seen Cubans in mid to late 1990s in a secret submarine base. Years later, a single picture became public of a small black native submarine in Havana harbor. It is rumored to be called 'Delfin' and is to be armed with two torpedoes. Only a single boat is in service and the design appears original, even if influenced both by North Korea and Soviet designs. The Cuban Navy rebuilt one, large ex-Spanish Rio Damuji fishing boat. BP-390 is now armed with two C-201W missiles, one twin 57 mm gun mount, two twin 25 mm gun mounts and on 14.5 mm machine gun. This vessel is larger than the , and it is used as a helicopter carrier patrol vessel. A second unit (BP-391) was converted and entered service in 2016. The Cuban Navy today operates its own missile systems, the made-in-Cuba Bandera (a copy of the dated Styx Soviet missiles) and Remulgadas anti-ship missile systems, as well as the nationally produced Frontera self-propelled coastal defence multiple rocket launcher. The navy's principal threats are drug smuggling