The P 4 class torpedo boat (TB), Soviet designation Project 123-bis and Project 123-K, were Soviet aluminum-hulled torpedo boats. They were armed with either two twin machine guns or a twin machine gun, and two torpedoes. A large number of them were exported to allied states such as North Vietnam and China. They saw service in a variety of conflicts including World War 2, the First Taiwan Strait Crisis, the Vietnam War and the Turkish Invasion of Cyprus. The P 4 torpedo boats consisted of two primary types; the Project 123-bis (B-123) type with machine guns, and the Project 123-K (K-123) type with added radar and 14.5 mm machine guns. Design and development The P 4 torpedo boats were developed from the pre-war prototype Komsomolets torpedo boat (Project 123) in 1942 due to the unsatisfactory performance of the G-5 type motor torpedo boat. The Project 123 was a single-step, hydroplaning design built from duralumin like the G-5. The prototype was built at the No.194 Marti yard in Leningrad in 1939, and after good test performance it was originally meant to replace it before the German invasion. Compared to the prototype Komsomolets, the new design, called Project 123-bis, had a flush deck hull, and were powered by American-supplied Packard petrol engines instead of the Soviet Mikulin GAM-34. The armament consisted of two twin DShK heavy machine guns, two 450 mm torpedo tubes, and 6 depth charges. Post-war, the Project 123-bis was identified as one of the more successful Soviet torpedo boat designs and production continued. As American-supplied engines dried up, new boats were built using Soviet M-50 diesel engines. A new variant, Project 123-K, was developed in 1950, with the addition of a radar and a single twin 14.5 mm KPV machine gun replacing the DShKs. Service history The first P 4 torpedo boats were delivered to the Soviet Baltic Fleet in 1944. On 11 April 1945, the boats TK-131 and TK-141 attacked and scored a torpedo hit against the German destroyer Z34, though they were unable to sink it. In 1951, the People's Republic of China purchased 46 P 4 torpedo boats from the Soviet Union, assigning them into 4 torpedo boat brigades. About 81-90 in total would be purchased from the Soviet Union from 1950-1955. The People's Liberation Army Navy would use them extensively in naval battles with the Republic of China Navy, most notably in 1954 when 4