The Tokyo Express (東京急行, Tōkyō kyūkō) is a term for regular flights by Soviet (and later Russian) military aircraft past Japan. They sometimes involve violations of Japanese airspace and have often been intercepted by fighter aircraft of the Japan Air Self-Defense Force. During the Cold War the flights tended to take place along the Sea of Japan side of the country. During the Cold War Tupolev Tu-16, Tupolev Tu-95 and Myasishchev M-4 aircraft were used. Some of them were transiting to or from Cam Ranh Base in southern Vietnam. The Soviet Union started using the base in 1979.