HMS Victorious, a British "Trident" nuclear submarine. Flickr/UK Ministry of Defence Naval Base Kitsap, a marine base 20 miles from Seattle, may be home to the world's largest single-location arsenal of nuclear weapons, and it's defended by dolphins trained by the US Navy.

"Nearly one-quarter of America’s 9,962 nuclear weapons are now assigned to the Bangor submarine base on Hood Canal, 20 air miles northwest of downtown Seattle," the Seattle Times reported in 2006.

Bangor was the name of a base that merged with another to form Kitsap in 2004.

"This makes Bangor the largest nuclear weapons storehouse in the United States, and possibly the world," according to the Seattle Times.

The United States' stockpile of nuclear weapons has fallen since 2006 thanks to a series of disarmament agreements with Russia. But most of those about which details are publicly known are equipped for launch via submarine, according to The Economist.

That explains why so much of the US stockpile would be positioned in a naval base on the Pacific Ocean, a part of the world towards which the US is in the midst of a strategic pivot.

Navy spokesman Chris Haley told Business Insider that the US Navy has used dolphins to defend the waters around the base since May 2010. Before then, according to another Navy spokesman, trained sea lions were also used to detect unwanted swimmers.

The Navy Marine Mammal Program at the Space and Naval Warfare Systems Command (or SPAWAR) in San Diego, California currently trains 85 dolphins and 50 sea lions for service in the US Navy.

A dolphin exposes a detecting device on its fin as it jumps from the sea during a patrol in Manama, Bahrain, on August 11, 2003. Hamad I Mohammed/Reuters When a dolphin finds a swimmer, the animals swim back to their trainers, who might give them a transponder to drop near the intruder.

Alternatively, according to Clayton Swansen, a dolphin handler who worked in the Navy program between 2003 and 2005, the marine mammals are equipped with a bite plate that holds a shackle that the dolphins can use to disable an intruder. "They just hit the person in the leg and it attaches around their leg and they can't pull it off until it sends a float up," Swansen told Business Insider.

The Navy has used dolphins to defend the American mainland before. The animals even helped provide security for the Republican National Convention of 1996, which took place at the waterside San Diego Convention Center less than a month after a bombing at the summer Olympics in Atlanta.