A civic group opposed to stationing a US nuclear-powered aircraft carrier in Japan has sued the government to halt harbor work being done to accommodate the warship, a lawyer said Tuesday. The US Navy is slated to deploy the USS George Washington next summer to Yokosuka, just south of Tokyo. The Nimitz-class carrier replaces the diesel-powered USS Kitty Hawk. The decision sparked a backlash in Japan, where feelings run strong over nuclear weapons. Japan is the only nation to have suffered a nuclear attack, and critics oppose the basing of a nuclear-powered warship in domestic waters. Japan's government has backed the idea, however, saying the George Washington would boost regional stability.