As Asian country rushes for better bombs, US fears time will run out

Behind the Trump administration’s sudden urgency in dealing with the North Korean nuclear crisis lies a stark calculus: a growing body of expert studies and classified intelligence reports that conclude the country is capable of producing a nuclear bomb every six or seven weeks.

That acceleration in pace — impossible to verify until experts get beyond the limited access to North Korean facilities that ended years ago — explains why President Donald Trump and his aides fear they are running out of time. For years, American presidents decided that each incremental improvement in the North’s program — another nuclear test, a new variant of a missile — was worrisome, but not worth a confrontation that could spill into open conflict.

Now those step-by-step advances have resulted in North Korean warheads that in a few years could reach Seattle. “They’ve learned a lot,” said Siegfried S. Hecker, a Stanford professor who directed the Los Alamos weapons laboratory in New Mexico, birthplace of the atomic bomb, from 1986 to 1997, and whom the North Koreans have let into their facilities seven times.

North Korea is threatening another nuclear test, which would be its sixth in 11 years. The last three tests — the most recent was in September — generated Hiroshima-size explosions. It is unclear how Trump would react to a test, but he told representatives of the U.N. Security Council at the White House on Monday that they should be prepared to pass far more restrictive sanctions, which U.S. officials say should include cutting off energy supplies.

“People have put blindfolds on for decades, and now it’s time to solve the problem,” Trump said.

He made his remarks after a Sunday night phone call on North Korea with Xi Jinping, China’s president, who urged Trump to show “restraint” with North Korea, according to a Chinese television report. White House officials said little about the call, and aides are trying to use Trump’s unpredictability to the greatest advantage, hoping it will keep the Chinese off balance and deter the North Koreans.

A Growing Arsenal

Inside the CIA, they call it “the disco ball.”

It is a round, metallic sphere, covered by small circles, that the North Korean leader, Kim Jong Un, is shown caressing in official photographs as if it were his crown jewel. And it may be: The sphere is supposedly a nuclear weapon, shrunken to fit inside the nose cone of one of the country’s growing arsenal of missiles.

U.S. intelligence officials still debate whether it is a real bomb or a mock-up that is part of the country’s vast propaganda effort. But it is intended to show where the country is headed.

Unless something changes, North Korea’s arsenal may well hit 50 weapons by the end of Trump’s term, about half the size of Pakistan’s. U.S. officials say the North knows how to shrink those weapons so they can fit atop one of its short- to medium-range missiles — putting South Korea and Japan, and the thousands of U.S. troops deployed in those two nations, within range. The best estimates are that North Korea has roughly 1,000 ballistic missiles in eight or so varieties.

But fulfilling Kim’s dream — putting a nuclear weapon atop an intercontinental ballistic missile that can reach Seattle or Los Angeles, or one day New York — remains a more complex problem.

As Hecker, a man who has built his share of nuclear weapons, noted last week, any weapon that could travel that far would have to be “smaller, lighter and surmount the additional difficulties of the stresses and temperatures” of a fiery re-entry into the atmosphere.

But the North has come further than most experts expected since the infancy of its program in the 1950s, when the Soviet Union began training North Korean scientists in nuclear basics.