DARPA is researching means to create "stealth shark spies":

Engineers funded by the US military have created a neural implant designed to enable a shark's brain signals to be manipulated remotely, controlling the animal's movements, and perhaps even decoding what it is feeling.

That team is among a number of groups around the world that have gained ethical approval to develop implants that can monitor and influence the behaviour of animals, from sharks and tuna to rats and monkeys. These researchers hope such implants will improve our understanding of how the animals interact with their environment, as well as boosting research into tackling human paralysis.

More controversially, 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.

Although I can't quite figure out how DARPA "gained ethical approval" for all of this, foremost in my mind, unfortunately (or perhaps fittingly), is one thing: "sharks with frickin' lasers!" ;-)