U.S. Vice President Joe Biden traveled to a U.S. air base outside Tokyo Wednesday to thank service members and their families for their assistance to the Japanese people after the March 11 earthquake and tsunami.

The visit was Mr. Biden's final stop before flying home at the end of a week-long trip that also took him to China and Mongolia.

Service members at the Yokota Air Base, in a Tokyo suburb, participated in a massive U.S. relief effort after the March disasters, which destroyed whole towns along Japan's northeastern coast and left more than 20,000 people dead or missing.

The aircraft carrier USS Ronald Reagan and 18 other U.S. warships took part in the effort known as Operation Tomodachi, which is Japanese for friends.

According to the U.S. Pacific Command, the U.S. 7th Fleet delivered more than 240 tons of humanitarian and disaster relief supplies to survivors of the earthquake and disaster in the first weeks after the disasters. The efforts including the delivery of 500,000 gallons of fresh water to support to efforts to cool the crippled Fukushima nuclear power plant.

Prime Minister Naoto Kan expressed his personal appreciation to the United States for the effort in April, saying it had proved that the nations “are true tomodachi,” sharing basic values such as democracy and respect for human rights.

Mr. Biden praised the courage and resolve of the Japanese people during a visit to some of the stricken areas Tuesday.

Earlier on his trip, the vice president sought to assure Chinese leaders that the U.S. economy remains strong despite an unprecedented downgrade by a debt-rating agency.

In Mongolia, Mr. Biden praised that nation's transition to multi-party democracy. He also thanked it for its contributions to military operations in Iraq and Afghanistan, as well as other peace-keeping operations.