In what Seoul called an act of "fanatic recklessness," North Korea carried out its biggest nuclear test yet early Friday, angering allies and enemies alike. The test registered as a 5.3-magnitude quake; Middlebury Institute expert Jeffrey Lewis tells Reuters that signals a blast of up to 30 kilotons, which would make the North Korean bomb bigger than the one the US dropped on Hiroshima in 1945. South Korean defense officials say the blast was closer to 10 kilotons, which is still nearly twice the size of the bomb Pyongyang is believed to have detonated in January, the Wall Street Journal reports. The nuclear test, which took place on the 68th anniversary of North Korea's founding, is the country's fifth. "This has definitely put on a higher level (the North's) technology of mounting nuclear warheads on ballistic rockets," said a statement out of the North.
Pyongyang says it will now be able to produce "at will" smaller nuclear warheads. The White House says President Obama, who is on his way home from Asia, spoke to South Korean President Park Geun-hye and Japanese Prime Minister Shinzo Abe after the test. China, Pyongyang's only major ally, slammed the country for conducting the test with "disregard" for international objections and said it's monitoring border areas for radiation. North Korea expert Koh Yu-hwan at Seoul's Dongguk University says the test may have been conducted to show that sanctions aren't hurting North Korea's nuclear program. "It seems that the North has decided to play an 'end game' where they push things to see how far they can go," he tells the AP. "It's already being heavily sanctioned and there will be little room for any new sanctions that will meaningfully hurt them more." (Read more North Korea stories.)