Japanese opposition parties and local officials on Sunday criticised a new military agreement with the United States, with one politician calling it "extremely dangerous".
The agreement on a major realignment of the alliance "is a radical change in security policies," said Seiji Mataichi, secretary-general of the Social Democratic Party of Japan.
"It has gone beyond the contents of the (1960) Japan-US Security Treaty. We cannot accept that," Mataichi said in a statement.
"The report, which authorises Japan's support and commitment for military action by the United States, is extremely dangerous," he said. On Saturday the two governments adopted an interim report designed to cut US forces in the Japanese island of Okinawa, deploy a powerful missile defence radar in Japan and bind their militaries more closely together.
Seiji Maehara, head of the Democratic Party of Japan, said in a television interview that the report would lift limits on Japan's military support for the United States.
"If there is no explanation about how the government wants to make a change, (the limit) will be chipped away gradually," Maehara said. "The government must ask people if the government can go ahead with redefinition" of the treaty.