In detonating North Korea’s most powerful nuclear bomb yet, Kim Jong Un is betting it’s too late for either U.S. President Donald Trump or Chinese leader Xi Jinping to be able to take away his atomic arsenal.

Kim’s regime claimed on Sunday it successfully detonated a hydrogen bomb that can fit onto an intercontinental ballistic missile, advancing its quest to be able to hit the U.S. with a nuclear weapon. Earlier in the day it said it now had a bomb with a maximum force topping 100 kilotons -- more than six times the magnitude of what the U.S. detonated over Hiroshima.

Regardless of whether it was actually a hydrogen bomb, the explosion was big enough to “pretty much end an American city” if strapped on an ICBM, according to Vipin Narang, an associate professor of political science at the Massachusetts Institute of Technology who focuses on nuclear issues. That makes it harder for either the U.S. or China to force Kim to back down, he said.

“I had thought that maybe Kim hadn’t tested number six for the past several months because that was a red line for China,” Narang said. “But clearly he decided to blow past it.”

The failure of the U.S. and China to find a common approach has allowed Kim to accelerate his nuclear weapons program, something he says is essential to deter an American invasion. With each provocation he appears to have gained confidence that the U.S. won’t resort to military action that could unleash World War III. Equally, he’s betting China won’t cut off the sales of oil and food that keep his regime afloat.

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North Korea carried out its test when both Trump and Xi had potential distractions: The U.S. president toured southern states devastated by Hurricane Harvey, while Xi is hosting leaders from Russia, India, Brazil and South Africa.

Trump did not respond immediately -- though he tweeted support for disaster relief efforts. In posts about eight hours later on Twitter he said North Korea’s actions remained hostile to America.

“North Korea is a rogue nation which has become a great threat and embarrassment to China, which is trying to help but with little success,” Trump said. “South Korea is finding, as I have told them, that their talk of appeasement with North Korea will not work, they only understand one thing!”

Xi didn’t mention North Korea in a speech at the BRICS meeting in Xiamen. In a statement on Sunday, China’s foreign ministry condemned the nuclear test and called on North Korea to “return to the track of dialogue.” Russia echoed those comments, with Deputy Foreign Minister Sergei Ryabkov saying the situation can only be solved through talks.

The timing during the BRICS summit “shows China cannot force North Korea to give up its nuclear missiles, and North Korea is increasingly hostile to China,” said Shi Yinhong, an adviser to China’s cabinet and international relations professor at Renmin University in Beijing. “Beijing is increasingly skeptical about the strategy to implement more sanctions.”

While China backed United Nations sanctions last month that cut a third of North Korea’s exports, it resisted tougher measures, particularly to cut off oil flows. China has long calculated that North Korea’s collapse may destabilize its economy and give the U.S. military greater influence in a unified Korea on its border.

Military Action

Trump, meanwhile, has repeatedly threatened China with punitive measures if it fails to do more on North Korea. The U.S. has launched a probe of alleged Chinese intellectual property violations, and slapped sanctions on some companies based in China that the U.S. accuses of conspiring with North Korea to evade sanctions.

The U.S. must consider a different approach to North Korea as the status quo responses have “very predictable” results, according to William McKinney, a visiting scholar at the U.S.-Korea Institute of the Johns Hopkins School of Advanced International Studies. Other options include “game-changing engagement” that reassures North Korea of its security or “kinetic military action” -- such as shooting down a missile or destroying launch sites.

The risk of U.S. military action is it provokes a response from North Korea that could devastate Northeast Asia. Seoul’s 10 million residents live just 35 miles (56 kilometers) from the border -- well within North Korea’s artillery range.

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“The discussions around North Korea have been far too narrow, focusing on nuclear weapons, when the real issue is what are the overall security requirements of North Korea, South Korea, China and Japan,” former U.S. Energy Secretary Ernest Moniz said in an interview on Sunday.

North Korea has said it won’t put its nuclear weapons up for negotiation unless the U.S. drops its “hostile” policies. While the U.S. and its allies say they’ll never accept North Korea as a nuclear state, the reality on the ground changes with each advancement: U.S. intelligence officials concluded that North Korea can miniaturize warheads to fit on missiles, and has as many as 60 nuclear bombs, the Washington Post reported last month.

“It’s safe to assume that North Korea has completed its nuclear program,” said Park Jiyoung, a senior research fellow of the science and technology policy program at the Asan Institute for Policy Studies in Seoul. “We probably saw its last nuclear test. If it comes with more nuclear tests in future, they’re probably intended to threaten, not to verify their technology.”

Further UN resolutions are likely to make little difference as China won’t fully participate in sanctions and there’s little the U.S. can do without risking a war in Asia, Andrei Lankov, a historian at Kookmin University in Seoul who once studied in Pyongyang, said by phone.

“North Korea will will never give up its ambition of attaining usable nuclear weapons,” Lankov said. “I don’t have enough fingers to count the number of times that North Korea has crossed an uncrossable red line with impunity.”

— With assistance by Keith Zhai, Kanga Kong, Sonia Sirletti, and Ilya Arkhipov

https://www.bloomberg.com/news/articles/2017-09-03/with-powerful-nuclear-bomb-kim-dares-trump-and-xi-to-stop-him