YOKOSUKA, Japan - Masahiko Goto simply does not want a nuclear power plant in his backyard. He says it is dangerous and unnecessary, and over the past year he's collected 324,000 signatures of others who feel the same way.

He's also pushed the U.S. Navy into a corner.

Goto is spearheading a high-profile movement to squelch the planned replacement of the USS Kitty Hawk with a more up-to-date nuclear-powered vessel. The Kitty Hawk is the oldest active duty ship in the Navy and the only U.S. aircraft carrier permanently deployed abroad.

For the moment, Goto's campaign appears to be winning.

The campaign has hit a sympathetic note with the Japanese public, which is often wary of changes in the U.S. military footprint. The country has also been rocked by a string of scandals and accidents that has undermined confidence in the safety of Japan's own nuclear power program.

The nuclear issue is getting added attention now, as Japan over the next two weeks marks the 60th anniversaries of the 1945 atomic bomb attacks on Hiroshima and Nagasaki, which killed more than 200,000 and hastened the collapse of military rulers.

"People are more concerned than ever before with the safety of nuclear power plants in general," said Goto, who is a lawyer. "So it doesn't take much for them to realize that the idea of having one floating on a military ship in Tokyo Bay, near a huge population center, is really frightening."

The swell of grass-roots opposition, which has won support from the local mayor and governor, has created a serious quandary for the Navy.

Struggling to respond to the growing threat of multiple crises around the world, the Navy has been working hard in recent years to get the most out of its carriers. The ships act as mobile airfields that are not subject to host country constraints when at sea and have proved indispensable in the Iraq and Afghanistan conflicts.

Though the aging Kitty Hawk is battle ready, it's something of an anachronism.

The Kitty Hawk and the Florida-based USS John F. Kennedy, commissioned respectively in 1961 and 1964, are the only carriers run by steam turbines left in service. Because the diesel-powered carriers are expensive to operate, the Kitty Hawk is due to be decommissioned in 2008.

The Bush administration had proposed decommissioning the Kennedy this year. Doing so, it argued, would save $1.2 billion over the next six years. But the anti-nuclear movement here - and opposition at home - has forced officials to rethink that plan.