"Type: Surface ship-and submarine-launched anti-submarine weapons.
Development: Little reliable information is available about Japanese torpedo programmes. Three anti-submarine weapons were reported to be used by the Japanese Maritime Self defence force, namely the Type 73, the Type 73 Mod and the Alliant Mark 46 Mod 5. The designation Type 73 is likely to apply to the Alliant Mark 44 lightweight torpedo which Japan is known to have purchased, but is no longer in first line service.

A replacement weapon whose experimental designation is GRX-3 is under development but progress has been slow."