Article title Destroyer Escort Sailors Association (DESA). The Shimushu-class kaibōkan, as with the Chidori class torpedo boat, was a consequence of the 1930 London Naval Treaty, which placed limitations on the total destroyer tonnage the Imperial Japanese Navy was permitted. However, due to many other priorities, the budget for this new class was not secured until the 1937 3rd Naval Armaments Supplement Programme.