American military and intelligence officials tracking North Korea’s actions by the hour say they are bracing for an imminent test of an intercontinental ballistic missile capable of reaching American shores, but appear resigned to the fact that President Trump has no good options to stop it.
If the North goes ahead with the test in the coming days — Pyongyang promised a “Christmas gift” if no progress had been made on lifting sanctions — it would be a glaring setback for Mr. Trump’s boldest foreign policy initiative, even as he faces an impeachment trial at home.
American officials are playing down the missile threat, though similar tests two years ago prompted Mr. Trump to suggest that “fire and fury,” and perhaps a war, could result.
Mr. Trump often cites the suspension of long-range missile and underground nuclear tests for the past two years as evidence that his leader-to-leader diplomacy with the North was working — and that such negotiating skills would persuade the North’s leader, Kim Jong-un, to give up his arsenal.
The administration’s argument has now changed. Should Mr. Kim resume tests, American officials say, it will be a sign that he truly feels jammed, and has concluded Washington will not lift crushing sanctions on his impoverished nation anytime soon.
Left unaddressed, however, is the challenge that a new missile test would represent, and what that would mean for the sanctions strategy. Over the past week, Stephen E. Biegun, the North Korea envoy who was confirmed by the Senate on Thursday as the next deputy secretary of state, has traveled across East Asia to also try to stem new efforts by Russia and China to weaken those sanctions.
Military officials say there are no plans to try to destroy a missile on the launchpad, or intercept it in the atmosphere — steps both Presidents George W. Bush and Barack Obama considered, and rejected. It is unclear if the military’s Cyber Command is still trying to sabotage the launches from afar, as it did under the Obama administration, with mixed results.
Instead, officials say, if the North resumes its missile tests, the Trump administration will turn to allies and again lobby the United Nations Security Council for tightened sanctions — a strategy that has been tried for two decades.
Beneath the recent threats is the onset of a cold reality: In the 18 months after Mr. Trump and Mr. Kim first met in Singapore, with declarations of warmth not seen since the suspension of the Korean War in 1953, the North has bolstered its arsenal of missiles and its stockpile of bomb-ready nuclear material.
New estimates from a leading authority suggest that Mr. Kim has expanded his arsenal substantially since Mr. Trump announced on Twitter after Singapore that “there is No Longer a Nuclear Threat from North Korea.”
Siegfried S. Hecker, the former head of the Los Alamos National Laboratory and one of the few Westerners who has seen the North’s uranium production facilities, says he believes the country has fuel for about 38 warheads — well beyond an earlier low-end estimate that he and other scientists and intelligence analysts had issued.
In recent weeks, the North has conducted ground tests of what appear to be new missile engines that Pyongyang said would bolster its “nuclear deterrent,” suggesting that it has little intention of giving up its ability.