The New Scientist reports that the military has gotten so-called "ethical approval" to put implants into animals that will allow the military to remotely control the animals.
". . . the Pentagon hopes to exploit sharks’ natural ability to glide quietly through the water, sense delicate electrical gradients and follow chemical trails. By remotely guiding the sharks’ movements, they hope to transform the animals into stealth spies, perhaps capable of following vessels without being spotted."
The military admits to using mammals in their programs, but denies that the animals are used for offensive purposes. During Hurricane Katrina in 2005, it was revealed that some of these animals are possibly trained for offensive purposes:
"Armed dolphins, trained by the US military to shoot terrorists and pinpoint spies underwater, may be missing in the Gulf of Mexico.
Experts who have studied the US navy’s cetacean training exercises claim the 36 mammals could be carrying ‘toxic dart’ guns. Divers and surfers risk attack, they claim, from a species considered to be among the planet’s smartest. The US navy admits it has been training dolphins for military purposes, but has refused to confirm that any are missing."
PBS also has some information about attack dolphins. PBS claims that there is no proof that dolphins were ever trained to attack humans, but if a dolphin can be trained to "tag" an enemy diver, what would stop the military from training the dolphins to neutralize an enemy diver?