Yugo class submarine

                           The Yugo class submarine is a class of four midget submarines used primarily for infiltration and espionage by North Korea. The class is so named because it was build to plans supplied to North Korea by Yugoslavia in 1965. In fact this class submarine is a family of midget submarines for that not all are identical. The displacement is either the standard 90 tons of the original Yugoslavian design for the early units, or 110 tons for the later units, while armament is either a pair of 400 mm torpedo tubes (early units) or a pair of 21 in short torpedo tubes (later units), however, all units have the same range: 550 nautical miles (1,020 km) at 10 knots (19 km/h) on the surface and 50 nautical miles (93 km) at 4 knots (7.4 km/h) submerged. Their final example was built in the 1980s, after which they were superseded by the Sang-O class submersibles. In 1998 one out of the 6 submarines was captured by the South Koreans. In July 2007, 4 were given to Iran to pay back some of North Korea's debts to Iran; the last one was retired but kept by the North Koreans.