US diplomats typically are unfailingly polite and reverential towards their countries of expertise and, upon retirement, go away quietly into research or business.

Not so with Kevin Maher.

Since he was unceremoniously removed from his position last year, the veteran US diplomat on Japan has gone on the offensive with biting criticism on issues from Tokyo's political paralysis to the Fukushima nuclear disaster.

To his own surprise, he has found an eager audience. A book he wrote in Japanese, "The Japan That Can't Decide," has sold more than 100,000 copies and for weeks topped the country's best-seller list for non-fiction paperbacks.

Maher's main thesis is that Japan -- which has had six new prime ministers since 2006 -- has been crippled by a failure of its politicians to accept responsibility and, hence, to make hard decisions.

Maher pointed to the crisis at the Fukushima Daiichi nuclear plant, which was devastated by the March 11 tsunami, and dismissed the government's declaration last month that it had stabilized the leaking reactors.

"It's not stable," Maher said recently at the Heritage Foundation in Washington. "Tokyo is safe, but Fukushima Daiichi is in really bad shape."

The State Department sacked Maher as its Japan desk chief just a day before the historic 9.0-magnitude earthquake but he stayed on for another month to coordinate the US disaster response.

Maher said that the US government was privately terrified over the unfolding crisis. He accused Japan's then prime minister, Naoto Kan, of evading responsibility and trying to pass the problem over to the plant's operator, the Tokyo Electric Power Co.

"I remember sitting on a task force many a time thinking, 'Who the hell is in control in Japan?' The government's not doing anything. Kan made one trip and flew up and got in the way and came back," Maher said.

Maher said that he watched in horror as he saw television footage of a sole helicopter dropping water on the stricken plant.

"Is that the best Japan can do?" Maher said. "Frankly what happened is the US government called in the Japanese ambassador and said, look, you have to take this stuff seriously. We don't know what's going to happen."

Maher said that the United States was even looking at whether it would have to evacuate some 100,000 Americans, although it soon became clear that Tokyo was not in harm's way.

Maher's earlier strident critiques led to his downfall. While in office, he spoke to students about Okinawa -- home to half of the 47,000 US troops in Japan -- and accused local leaders of playing on mainland Japanese guilt to "extort" concessions. Japanese media accounts of his remarks stirred outrage.

Maher, 57, who has worked on Japan for three decades and has a Japanese wife, called the controversy "water under the bridge" and said he was making a good living as a consultant.

Nonetheless, he criticized the two officials he said were behind his dismissal -- then deputy secretary of state Jim Steinberg and Ambassador to Japan John Roos.

"They just wanted to get this out of the press and decided that the best thing was not to address whether these press reports were actually true or not but just to remove me from my position," Maher said.

Despite his criticism, Maher -- like current US officials -- sees bright spots in Japan's latest prime minister, Yoshihiko Noda, who is pushing forward controversial plans to raise taxes and join talks on a US-backed trade pact.

Maher said he has received little backlash over his book. He believed he won over potentially hostile readers with a message that Japan worked well in the past and needed to return to its traditions.

"We used to have an image back in the '80s, if a Japanese corporation had a problem, you were worried that the chairman would go to commit seppuku," he said, referring to ritual suicide.

"He would take responsibility even if it was not a mistake that he made. But now it's reversed in Japan," he said.

Maher said he was surprised when he visited Okinawa to promote his book.

"There were four demonstrators. When I was consul general in Okinawa, I could always get 40."