February16, 2007: The U.S. Navy is sending 30 trained dolphins and sea lions to help guard a submarine base in Puget Sound (near Seattle, Washington) against hostile swimmers. The dolphins are trained to either drop beacons, if they spot a swimmer, or slip a cuff around a swimmers leg. The cuff is attached to a rope, and this allows the dolphins handler to reel in the swimmer.

In 2003, some of these sea mammals were sent to the Persian Gulf to guard against hostile swimmers getting near coalition ships or port facilities with bombs. Called the "Mk 6 anti-swimmer dolphin system", the dolphins normally work with Explosive Ordnance Disposal units. This is because the dolphins are mainly trained to search for underwater explosives and mines, using their natural sonar ability. About as intelligent as dogs, each dolphin bonds with its handler. Without that bond, dolphins could just wander off and not come back when turned loose to work. Occasionally a dolphin will disappear for a few days, particularly when there are wild dolphins in the area. But dolphins and sea lions are pack animals, and it is difficult for a domesticated sea mammal to be accepted into a group living in the wild.

The U.S. Navy has been training the sea mammals since the 1960s, and has found that they are as trainable as dogs, but live twice as long. When too old to work, dolphins and sea lions are retired to a facility which feeds them, looks after their health and lets them out for swims in the open water. These are domesticated animals, and prefer the company of humans. Because they work under water, these animals don't get a lot of attention in the media.