The incumbent leader of the Democratic Party of Japan said Monday that Japan should review the five principles under which the Self-Defense Forces are dispatched to a United Nations-led peacekeeping operation.

Naoto Kan argued that the dispatch of the SDF should be considered for a possible U.N. peacekeeping mission for East Timor, even if it would be an exception to the five principles, which require neutrality among warring parties.

The principles attach strict conditions to any overseas dispatch of the SDF, including neutrality, establishment of a ceasefire agreement and the consent of conflicting parties.

"The will of (the East Timorese) for independence has been clearly expressed (through this month's referendum). We should take measures in accordance with that," Kan said during a panel discussion at the Japan National Press Club in Tokyo in which the party's three presidential hopefuls held a joint news conference.

Yukio Hatoyama, DPJ deputy secretary general and Kan's chief rival in the Sept. 25 election, argued that the five principles should be maintained and that an SDF dispatch to East Timor could violate the pacifist Constitution.

"I believe the five principles should be observed," said Hatoyama, who is widely believed to be leading the three-way race.

The other candidate, DPJ executive council chief Takahiro Yokomichi, argued that a variety of contributions toward East Timor should be considered in addition to any SDF dispatch, such as humanitarian aid and support for nongovernmental organizations.