In response to the North Korean seizure of the U.S. spy ship Pueblo, an armada of ships and subs were sent into the Sea of Japan, including the USS Swordfish, a nuclear-powered submarine. Unfortunately, while conducting a covert surveillance operation off the coast of Vladivostok, Swordfish‘s mast struck a block of ice. So she departed the area for the U.S. Naval Base at Yokosuka, Japan for repairs. When tthe Russians saw a photo of the damaged Swordfish in a Japanese newspaper, they (wrongly) assumed the damage resulted from a collision with their nuclear-armed submarine K-129.