Robert Gates is expected to urge Japanese government to resume an Indian Ocean naval refueling mission in support of U.S.-led coalition operations in Afghanistan .
Japan, Washington's top ally in Asia, withdrew its Indian Ocean contingent after the government failed to reach a compromise with the main opposition party, which is against the mission.
While U.S. officials have said coalition operations in Afghanistan will not be seriously impaired by Japan's withdrawal, they have expressed disappointment over it.
Gates was scheduled to meet with Prime Minister Yasuo Fukuda, Defense Minister Shigeru Ishiba and other top government officials during his three-day Tokyo visit, Japan's Foreign Ministry said.
Japan's military has refueled coalition warships in the Indian Ocean since 2001, and sent ground troops to Iraq in 2004-06.
Japan hosts about 50,000 U.S. troops under a mutual security pact, and Washington and Tokyo are cooperating over a mutual missile defense system aimed at preventing attacks by North Korea.
Fukuda plans to travel to Washington for talks with U.S. President George Bush later this month, according to news reports.
French President Emmanuel Macron does not exclude sending NATO troops to Ukraine for security in Europe and for Russia's defeat in the conflict. There is currently no consensus on the need to send NATO troops to the country