The Japanese government withheld information about the full danger of last year's Fukushima nuclear plant disaster from its own people and from its key ally, the United States, an independent investigation has found.
A report by the Rebuild Japan Initiative Foundation said the decision may have put US-Japan relations at risk in the first days after the accident.
The report, compiled over six months from interviews with more than 300 people, delivers a scathing view of how leaders played down the risks of last March's meltdowns at the Fukushima Dai-ichi nuclear plant following a massive earthquake and tsunami.
Meanwhile, tsunami waves generated by the magnitude-9 earthquake in Japan last March dragged between three million and four million tons of debris into the ocean after tearing up harbours and homes.
Scientists believe ocean currents are carrying some of the lumber, refrigerators, fishing boats and other objects across the Pacific toward the United States.
University of Hawaii senior researcher and ocean current expert Nikolai Maximenko said 1%-5% of the one million to two million tons of debris still in the ocean may reach Hawaii, Alaska, Oregon and Washington and British Columbia.
Some debris appears to have already arrived, like half a dozen large buoys suspected to be from Japanese oyster farms found in Alaska late last year.