TOKYO » Early in the Fukushima nuclear crisis, U.S. officials felt that nobody in Japan’s government was taking charge, and Washington considered evacuating American troops in a worst-case scenario, a retired U.S. envoy said.

When the March 11 earthquake and tsunami set off the crisis by crippling the Fukushima Dai-ichi plant and sending it toward meltdown, Prime Minister Naoto Kan’s administration initially acted as if it was the plant operator’s problem, not the government’s, former diplomat Kevin Maher said Thursday.

"There was nobody in charge. Nobody in the Japanese political system was willing to say, ‘I’m going to take responsibility and make decisions,"’ said Maher, who coordinated U.S. offers to help Tokyo deal with the crisis.

"Nothing was taking place at Fukushima Daiichi in terms of the government solving the problem" until about a week later when Tokyo and Washington launched a joint task force, he told a news conference.

An official at the Japanese prime minister’s office highlighted the "difficult circumstances in the post-quake situation," including getting relief to thousands of tsunami victims as well as managing the nuclear crisis.

"The government of Prime Minister Kan was doing its utmost to handle this situation, so we don’t accept this criticism," said Noriyuki Shikata, deputy Cabinet secretary for public relations.

Maher, a former director of the U.S. State Department’s Japan office, had been dismissed for allegedly making insulting remarks about Okinawan people in an off-the-record talk with university students in December. But he was called back for duty on the task force when the crisis struck, and his retirement was postponed until April.

Maher coordinated more than 100 American nuclear, defense and other officials dispatched by Washington to work with the Japanese government as the reactors rapidly deteriorated.

Japan initially was not forthcoming with details of the crisis, while independent U.S. information indicated at least two of the plant’s six reactor cores were melting down, he said.

"We were very worried about what was going to happen to Japan," he said, adding that U.S. officials drafted a plan to evacuate some of the nearly 50,000 Japan-based American service people in a worst-case scenario involving plumes of radiation. They also considered evacuating nearly 100,000 American civilians in Tokyo, but eventually recommended only a 50-mile (80-kilometer) evacuation zone.

"The worst-case scenario was, ‘Would you have to move U.S. forces out of Japan if there were threat of radiation?"’ he said.

"Fortunately, that did not happen," he said, because such a pullout could have caused a "tremendous negative impact" on the U.S.-Japan security relationship.

It took Japan about two months to acknowledge that the cores of three reactors at Fukushima had melted in the first few days of the crisis.

Plant operator Tokyo Electric Power Co. said Wednesday that the reactors are still leaking small amount of radiation — about one 10-millionth of the amount released after several explosions in mid-March that eventually forced about 100,000 people to evacuate their homes. TEPCO and the government say they plan to bring the reactors to a stable shutdown state by early January.

Maher said he sympathized with Japanese evacuees and expressed optimism that their communities could be cleaned up and restored.

"It can be done," he said, adding that it requires a huge expenditure and a very "decisive approach."