Since the late 1950's, when scientists have done research towards analysing the dolphins hydrodynamics and sonar, militaries hoped it could learn from the dolphins to improve its own vessels. In the early 1960's, the work of scientists investigating dolphin communication and intelligence alerted that dolphins possessed a great intelligence and they were able to learn tasks quickly and efficiently.
Subsequently, the USA and USSR navies started "secret" dolphin research and carried out a wide variety of experiments to determine whether dolphins could be trained to locate and retrieve "lost" objects from the seabed using its sonar. They wanted to use dolphins to replace expensive electronic equipment and human divers.
Early, some reports let the people know about these plans and somebody starts to suspect that cetaceans could be exploited or abuse. Rumors said that military dolphins have been trained to lay underwater mines, to locate enemy combatants, or to seek and destroy submarines using kamikaze methods.
The US Navy has denied having trained its animals to harm or injure humans in any fashion or to carry weapons to destroy ships and went on with the programs and ahead with training oceanic dolphins and other marine mammals for several reasons as to rescue lost naval swimmers or to locate underwater mines.
Most recently, military marine mammals were used by the U.S. Navy during the First and Second Gulf Wars. The media let the world know the existence of Zack the Sea Lion who was deployed to Iraq for "Enduring Freedom" In fiscal year 2007, the United States Navy donated $14 million to marine mammal .Russian military is believed to have closed its marine mammal program in the early 1990s. In 2000, the press reported that dolphins trained to kill by the Soviet Navy had been sold to Iran
Dolphins are trained much as police dogs and hunting dogs are. They are given rewards such as fish on correct completion of a task. A team of humans take care of the military marine mammals: highly trained technicians, veterinarians and marine biologists work full-time keeping the dolphins, sea lions and other mammals healty and “fit for duty”. They use routine physicals, nutrition oversight, and extensive data collection and management.
The bad notice was been said by some ex-navy trainers that the dolphins have been beaten, kicked and otherwise mistreated.
Military dolphins had been, and are, treated in fiction. The most famous about it are the film “The Day of the Dolphin” (Mike Nichols, 1973) and the TV Series seaQuest DSV where a trained dolphin, Darwin, is a member of the crew.
In the “Star Trek: The Next Generation” by Rick Sternbach there are multiple cetacean operations and dolphins armed with sonar cannons were also portrayed in the video games “Red Alert”