YOKOSUKA NAVAL BASE, Japan — On March 14, 2011, Japanese government and U.S. military officials were busy calming concerns about the Fukushima Dai-ichi nuclear plant disaster.

Nearly a year later, documents and reports make the case that the restrained sentiments of that day came while Japan’s top officials worried that the disaster could have forced the evacuation of millions living in the Tokyo region, 150 miles to the south.

Three days after the devastating tsunami knocked the nuclear power plant offline, the United States had limited information on the damaged plant’s condition beyond what came from the Japanese government, according to Stars and Stripes interviews and Japanese reports.

Meanwhile, the Japanese government was struggling to get information from Tokyo Electric Power, known as Tepco, according to a 400-page report scheduled to be released soon by the Rebuild Japan Initiative Foundation, an independent fact-finding committee. The committee of professors, lawyers and journalists interviewed more than 300 people over six months, including former Prime Minister Naoto Kan, according to a pre-release summary of the report.

On March 14, then-Japanese cabinet secretary and chief government spokesman Yukio Edano personally feared a “demonic chain reaction” spreading toward Tokyo, according to an interview with Edano contained in the full report, which was shared in advance with select media outlets.

In the report, the spokesman explained that if Tepco evacuated all of its workers from the Dai-ichi plant — as the company’s president wanted to do — the resulting increase in fallout from the abandoned plant could have spurred workers in successive plants to the south to evacuate as well. The ensuing plant failures would have threatened the Tokyo metropolitan area, Edano said.

Critics have suggested recently that this scenario was unlikely, and that abandoning each plant would have exhibited a massive failure in leadership.

Nevertheless, the report contrasts the behind-the-scenes concerns of Edano, Kan and others in government with public statements that downplayed the damage to the crippled plant.

Naoki Kumagai, an official at Japan’s Nuclear and Industrial Safety Agency, said on March 14 that there was no need to be overly alarmed by the rise in radiation levels at Dai-ichi, according to The Associated Press.

That same day, Japan’s science ministry provided its data to U.S. forces about the crippled plant, even before informing the Japanese public. Defense Department officials would not provide the data to Stars and Stripes, saying it would be inappropriate to discuss internal information from the Japanese government.

That evening, now-retired U.S. Naval Forces Japan commander Rear Adm. Richard Wren told a military audience that the nuclear catastrophe was not a direct threat to Yokosuka Naval Base, some 150 miles to the south.

Wren, like leaders at other bases on Japan’s main island of Honshu, compared the tiny amounts of radiation being recorded on base to everyday items like X-rays, commercial flights and even bananas.

“Fukushima can’t get big enough to drive us to an evacuation,” Wren told Stars and Stripes following the meeting.

Three days later, the military announced a “voluntary departure” that saw roughly 10,000 family members and civilians leave the country at U.S. government expense.

Wren’s March 14 comments appear to have come before the United States had gathered much data of its own on the damaged reactor, and two days before Japanese government officials felt assured that Tokyo would escape a worst-case scenario.

“In hindsight, March 15 turned out to be a crucial turning point,” the committee report stated. “An early morning accident at Unit 2 led to a dramatic rise in the diffusion of radioactive materials.”

It wasn’t until at least March 14 that U.S. forces began flying search patterns with Department of Energy systems onboard designed to assess radiation, U.S. Forces Japan commander Lt. Gen. Burt Field said in a July interview with Stars and Stripes. For days afterward, U.S. experts modeled the growing radioactive plume blowing away from the plant to get a more complete picture.

As the U.S. was flying its data-gathering missions, Tepco president Masataka Shimizu was calling then-Prime Minister Kan and telling him that the company should evacuate its entire staff from the power plant, according to the report. Multiple hydrogen explosions had destabilized the plant.

Had Kan not rebuffed Shimizu, officials cited in the report concluded that additional power plants might have melted down and caused a far greater disaster.

“We barely avoided the worst-case scenario, though the public didn’t know it at the time,” said Yoichi Funabashi, the foundation founder, according to The New York Times.

It wasn’t until March 16 that a Japanese Self-Defense Force helicopter’s flyover of one of the reactors alleviated government fears of that worst case, according to the report.

Even before that certainty, parts of the Japanese government had decided the prudent approach would be to not reveal what they thought they knew.

In a leaked document signed by Japan’s former science minister, top bureaucrats reportedly decided on March 15 that data predicting the spread of radioactive substances “could be by no means released to the public,” according to a Kyodo news report.

Last week, Japanese officials said that the contents of that document were inaccurate, according to Kyodo.

The recent reports underscore the suspicions of many Japanese. An Associated Press-GfK poll last August found that 80 percent felt deeply that leaders were not telling them the truth about the crises. The Trust Barometer, a survey conducted by Edelman Digital that measures trust in institutions across 25 countries, found in February that only 8 percent of Japanese trust the government to tell them the truth.

There is nothing to indicate that the U.S. military declined to release radiological information based on Japan’s reluctance, thought it has still not released data collected by U.S. military environmental teams in northern areas where U.S. personnel worked during Operation Tomodachi.

As Operation Tomodachi developed, briefings to Japan-based commands, headed by Pacific Command chief Adm. Robert Willard, included diagrams and weather forecasts on the movements of radiation at the time, said Navy spokesman Jon Nylander, who sat in on the daily briefings.

“As far as I know, I didn’t hear anybody saying ‘The Japanese are saying this, but don’t tell anybody,’ ” Nylander said.

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