The Democratic Party of Japan said Monday it is against extending the Self-Defense Forces mission in support of NATO forces in Afghanistan, a day after it won a stunning election victory over Prime Minister Shinzo Abe's ruling coalition.

The Maritime Self-Defense Force has provided fuel for multinational warships in the Indian Ocean since November 2001 under a special antiterrorism law, which has been extended four times, most recently May 1. The current mission is set to expire in November.

"We have always been fundamentally opposed to extending this law," said DPJ Secretary General Yukio Hatoyama. "The Upper House elections have shown the country agrees, and so we will be expected to keep that line."

The Indian Ocean dispatch has been part of Japan's recent attempts to raise its international profile. It also sent noncombat troops to help rebuild southern Iraq following the U.S.-led invasion.

The DPJ has criticized both operations, saying Japan's international efforts should be channeled through the United Nations, not the United States. Others say the missions violate the pacifist Constitution, which prohibits the use of force in solving international disputes.

Although the Liberal Democratic Party and its junior coalition partner New Komeito lost control of the Upper House on Sunday, Abe could still force an extension to the mission because the LDP controls the more powerful Lower House, which can override a vote in the upper chamber with a two-thirds majority.

Still, Abe's loss at the polls, which has been widely interpreted as a loss of mandate, may force the embattled leader to make policy concessions to the DPJ, which has emerged as the largest force in the Upper House.