Naoto Kan, secretary general of the Democratic Party of Japan, said Tuesday that the nation's largest opposition force cannot support U.S. plans to attack Iraq without sufficient proof it is developing weapons of mass destruction.
During a speech to the Japan Society here, Kan also said that concrete evidence of Iraq's "alleged assistance to terrorist groups like al-Qaeda" is also necessary.
Washington is currently considering whether to wage an offensive aimed at toppling Iraqi President Saddam Hussein.
Regarding speculation over a possible bid for the DPJ presidency next month, Kan said, "I will make up my mind after my return (to Japan on Saturday)."
Kan, 55, is on a six-day tour of the U.S. at the invitation of the Center for Strategic and International Studies, a Washington think tank.