Boatloads of Japanese protesters met the nuclear-powered aircraft carrier USS John C. Stennis (search) as it pulled into port in southern Japan on Saturday.

About a dozen boats were filled with demonstrators at Sasebo (search) port, while others on the dock punched their fists into the air and chanted, "Keep out nuclear-powered aircraft carriers!"

Japan is the only country ever to have suffered an atomic attack -- the World War II (search) bombings of Hiroshima and Nagasaki -- and there are strong concerns about the military use of atomic energy, and port calls by U.S. nuclear-powered vessels.

The 97,000-ton Stennis, based in San Diego, Calif., was stopping in Japan to participate in drills with the USS Kitty Hawk and Japan's Self-Defense Forces, said public broadcaster NHK.

Seven of the U.S. Navy's 12 carrier strike groups were deployed simultaneously around the globe this summer. The deployment to Japan was part of the first-of-its-kind "Summer Pulse" exercises, which the U.S. Navy launched to test the feasibility of having multiple detachments at sea, according to news reports.

U.S. military officials were unavailable for comment.

The Stennis, with its crew of 4,500, is expected to leave Sasebo Wednesday, NHK said.

Sasebo, on Japan's main southernmost island of Kyushu, is located 610 miles southwest of Tokyo.