via: The Telegraph
The Soviet Union began training dolphins and other marine mammals to locate mines, mark underwater and obstacles and detect – and if necessary kill – enemy frogmen in the 1960s.
The program is shrouded in myth, but the mammals are believed to have been trained to kill frogmen with special harpoons or knives fitted to their backs, or drag them to the surface to be captured.
They were also reported to be fitted with packets of explosives and trained to carry out suicide attacks against enemy vessels, using their natural sonar to distinguish Soviet submarines from potential targets.
With the collapse of the Soviet Union in 1991, Ukraine inherited both the animals and the experts who trained them.