The Obama administration on Thursday voiced its appreciation for Japan's efforts to fight extremists in Afghanistan, saying it hopes that the Japanese government could continue to support the U.S. operation.

The Japanese government has said that it would end its nearly eight-year-old refueling mission in support of U.S.-led operation in Afghanistan.

"First and foremost, we want to thank the government of Japan for its contributions to our efforts to fight extremism in Afghanistan. Japan's contributions have been very important, and we greatly appreciate everything that Japan has done in that regard," said State Department spokesman Robert Wood.

"We hope that Japan will find a way to continue to support the operations in Afghanistan, but that will be up to the Japanese government," said the spokesman.

Japanese Defense Minister Toshimi Kitazawa said that the refueling mission would end based on the law when its current legal mandate expires in January, 2010, but suggested that Japan could continue to provide support in an alternative way.

Reports here said the Japanese government led by Yukio Hatoyama, who claims that Tokyo should take more humanitarian measures in Afghanistan, could present a new plan on supporting the U.S.-led operation when President Barack Obama pays his first visit to Japan on November 12.

The Obama administration, who vowed to disrupt, dismantle and defeat al-Qaeda and its extremist allies, has been reviewing an overall strategy of the war in Afghanistan, and considering whether to send additional troops to the country.

General Stanley McChrystal, top U.S. commander in Afghanistan, warned that the United States would lose the war against al-Qaeda and Taliban without rapidly sending up to 40,000 additional troops to Afghanistan.

By the end of this year, according to previous deployment plans, there will a total of 68,000 U.S. troops in Afghanistan.

U.S. Defense Secretary Robert Gates will visit Japan next week and meet senior government and military officials on the "transformation of the alliance" between the United States and Japan. Korean Peninsula's nuclear crisis and Afghanistan's situation are expected to top agenda of Gates' visit.