"The MK-46 torpedo is designed to attack high performance submarines and is presently identified as the NATO standard. The MK-46 is designed to be launched from surface combatant torpedo tubes, ASROC missiles and fixed and rotary wing aircraft. In 1989, a major upgrade programme was begun to enhance the performance of the MK-46 Mod 5 in shallow water. Weapons incorporating these improvements are the Mod 5A and Mod 5A (S) torpedoes. The MK 46 Mod 5A torpedo is the backbone of the US Navy's lightweight ASW inventory and is expected to remain in service until the year 2015. The MK-46 originated with the RETORC I (Research Torpedo Configuration I) conducted by the US Naval Undersea Centre (NUC) at Pasadena CA."