Japan's defense ministry Wednesday deployed three planes to collect possible radioactive material following North Korea's claimed hydrogen bomb test, officials said.

Wednesday's nuclear test was the North's fourth after previous ones in 2006, 2009 and 2013, though many experts cast doubt on Pyongyang's claim that it was a successful test of a hydrogen bomb.

The results collected by the planes are expected to be released on Thursday, an official with Japan's Nuclear Regulation Authority told reporters.

Last month North Korean leader Kim Jong-Un suggested Pyongyang had already developed a hydrogen bomb, though the claim was questioned by international experts

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