Yukio Hatoyama, leader of the Democratic Party of Japan, on Sunday said that the Constitution should provide for "national forces" rather than "self-defense" services.
And once such a provision is made, he said, Japan should not deny itself the right to wage war.
Appearing on a Sunday morning television program, the leader of the nation's top opposition party stressed the need for the Constitution to be reviewed, saying, "From a global perspective, the Self-Defense Forces are by all means military forces."
Japan renounces war and the use of force as a means of settling international disputes in Article 9 of the postwar Constitution, which also says land, sea and air forces will never be maintained.
The government, however, has long taken the view that Japan has the right to self-defense. It created the Ground, Air and Maritime Self-Defense Forces in 1954.
"The contradiction must be eliminated," Hatoyama said, adding that the Constitution should provide for "national forces."