"We are very confident that Japan will recover and will be a very strong economic and global player for years and decades to come," Clinton told Prime Minister Naoto Kan during a brief visit to Tokyo intended as a morale boost to the crucial U.S. ally.

Kan thanked Clinton for U.S. help with the crises triggered by a magnitude-9.0 earthquake on March 11 that unleashed a massive tsunami, wrecking cooling and power systems at a nuclear plant that has been leaking radiation ever since.

"We will never forget and we will keep in our memory that the U.S. has provided such robust support," said Kan, in comments suggesting the aid has helped soothe friction over an American military base in Okinawa that forced his predecessor, Yukio Hatoyama, to resign last year.

Relief operations mounted by American soldiers after the earthquake and tsunami helped show a new and welcome face for troops the Japanese have hosted — sometimes grudgingly — for decades.

Roughly 20,000 U.S. troops were mobilized in "Operation Tomodachi," or "Friend," the biggest bilateral humanitarian mission the U.S. has conducted in Japan. The U.S. is also helping Japan cope with its nuclear crisis.

Kan has pledged to beef up disaster preparedness and make his top priority resolving the crisis at the tsunami-wrecked Fukushima Dai-ichi nuclear plant.

Tokyo Electric Power Co., the operator of the plant, announced Sunday a plan to bring the crisis under control within six to nine months, aiming to end radiation leaks that have forced the evacuation of tens of thousands of people.

"We would like to see evacuees return to their homes as early as possible," said TEPCO Chairman Tsunehisa Katsumata.

Clinton said Foreign Minister Takeaki Matsumoto, who she met with earlier, told her that Japan hoped for U.S. feedback on the plan.

"The constant efforts to respond to the situation at Fukushima have required intense analysis by Japanese, American and international experts, and we have been very supportive of what Japan is doing to take the appropriate steps," she said.

Clinton and Matsumoto announced the formation of a public-private partnership to encourage investment in the recovery effort. The aim is to keep American businesses interested in Japan by demonstrating its ability to bounce back from daunting natural disasters.

"There has been a great outpouring of concern, sympathy and admiration for the great resilience and spirit the Japanese people have shown throughout this very difficult experience," Clinton said.

Clinton, who called Japan’s well-being a "bedrock priority," also met with the Japanese emperor and empress. She was due to return to the U.S. later Sunday.

"I am so, so sorry for everything your country is going through. If there is anything we can do …" Clinton said to Emperor Akihito and Empress Michiko, who have been visiting evacuation centers near Tokyo and plan visits to areas hardest hit by the disasters in coming weeks.