At the start of Donald Trump’s presidency, American intelligence agencies told the new administration that while North Korea had built the bomb, there was still ample time - upward of four years - to slow or stop its development of a missile capable of hitting an American city with a nuclear warhead, The New York Times reports referring to to former and current employees of intelligence agencies.
The North’s young leader, Kim Jong-un, faced a range of troubles, they assured the new administration, giving Mr. Trump time to explore negotiations or pursue countermeasures. One official who participated in the early policy reviews said estimates suggested Mr. Kim would be unable to strike the continental United States until 2020, perhaps even 2022.
Mr. Kim tested eight intermediate-range missiles in 2016, but seven blew up on the pad or shattered in flight — which some officials attributed partly to an American sabotage program accelerated by President Barack Obama. And while the North had carried out five underground atomic tests, the intelligence community estimated that it remained years away from developing a more powerful type of weapon known as a hydrogen bomb.
Within months, those comforting assessments looked wildly out of date.
At a speed that caught American intelligence officials off guard, Mr. Kim rolled out new missile technology - based on a decades-old Soviet engine design, apparently developed in a parallel program - and in quick succession demonstrated ranges that could reach Guam, then the West Coast, then Washington.
And on the first Sunday in September, he detonated a sixth nuclear bomb. After early hesitation among analysts, a consensus has now emerged that it was the North’s first successful test of a hydrogen weapon, with explosive force some 15 times greater than the atom bomb that leveled Hiroshima.
The C.I.A. and other American intelligence services had predicted this moment would come, eventually. For decades, they accurately projected the broad trajectory of North Korea’s nuclear program. Yet their inability to foresee the North’s rapid strides over the past several months now ranks among America’s most significant intelligence failures, current and former officials said in recent interviews.
That disconnect — they saw it coming, but got the timing wrong — helps explain the confusion, mixed signals and alarm that have defined how Mr. Trump’s untested national security team has responded to the nuclear crisis.
In an interview, Lt. Gen. H.R. McMaster, Mr. Trump’s national security adviser, acknowledged that Mr. Kim’s race to the finish line — a bid to establish the North as a nuclear power before any negotiations begin or sanctions take a more punishing toll — “has been quicker and the timeline is a lot more compressed than most people believed.”
As a result, he argued, “we have to do everything we are doing with a greater degree of urgency, and we have to accelerate our own efforts to resolve the issue short of conflict.”