WASHINGTON — Returning to Washington on Wednesday, President Trump amplified claims of a highly successful summit with North Korean leader Kim Jong Un as Democrats — and some Republicans — grew increasingly skeptical about what had been accomplished in Singapore.
In tweets that began as Air Force One landed, Trump declared that there is ‘‘no longer’’ a nuclear threat from the rogue regime and lashed out at those who questioned what he had achieved, branding the media as ‘‘Our Country’s biggest enemy.’’
Trump’s glowing assessment followed the high-profile summit, which yielded a renewed promise by Kim to ‘‘denuclearize’’ the Korean Peninsula that was scant on details. Though many lawmakers and analysts have applauded Trump’s efforts, questions persisted Wednesday about what fundamentally had changed.
Trump, who has touted what he said was the trust built with the North Korean leader over the course of a few hours, cast his meeting as a game-changer that had already dramatically reduced the possibility of military conflict.
‘‘Just landed — a long trip, but everybody can now feel much safer than the day I took office. There is no longer a Nuclear Threat from North Korea,’’ the president said on Twitter.
In another tweet, Trump said North Korea is no longer the United States’ most dangerous problem, as Barack Obama had characterized it upon leaving the Oval Office — and he said Americans could ‘‘sleep well tonight!’’
Meanwhile, Secretary of State Mike Pompeo said that he expected “major disarmament” in North Korea within 2 1/2 years, representing significant headway in the standoff over the country’s nuclear arsenal before the end of Trump’s first term in office.
Pompeo said the administration hoped to move quickly.
North Korea has already spun the results of the summit in its favor, claiming it had won major concessions from the United States during its discussions with Trump.
The authoritarian country’s state-controlled news media said that Trump had promised to eventually lift sanctions against the North and to end joint military drills with South Korea. It also said the United States had agreed to a phased, “step-by-step” denuclearization process for the North, rather than the immediate dismantling of its nuclear capability.
Trump had said Tuesday the sanctions would stay in place until North Korea dismantled enough of its nuclear program to make it difficult to reverse course. Trump said the denuclearization process would begin “very soon” and happen “very quickly.”
But the North’s official Korean Central News Agency said the two leaders had agreed to a phased process in which Pyongyang would bargain away its nuclear arsenal in stages, securing reciprocal actions from the United States at each step.
Trump’s rosy assessment of the summit was ridiculed by Democratic lawmakers and some analysts, who suggested that North Korea remains a serious threat.
‘‘What planet is the president on?’’ Senate minority leader Charles Schumer of New York said during remarks on the Senate floor. ‘‘Saying it doesn’t make it so. North Korea still has nuclear weapons. It still has ICBMs. It still has the United States in danger. Somehow President Trump thinks when he says something it becomes reality, if it were only that easy, only that simple.’’
‘One trip and it’s “mission accomplished,’’ Mr. President? North Korea is a real and present threat.’
Representative Adam Schiff, Democrat of California, also mocked Trump, saying on Twitter: ‘‘One trip and it’s ‘mission accomplished,’ Mr. President?’’
‘‘North Korea is a real and present threat,’’ Schiff said. ‘‘So is a dangerously naive president.’’
Richard Haass, the president of the Council on Foreign Relations, said ‘‘the summit changed nothing.’’
‘‘Worse yet, overselling the summit makes it harder to keep sanctions in place, further reducing pressure on NK to reduce (much less give up) its nuclear weapons and missiles,’’ Haass said on Twitter.
A document signed by Trump and Kim provided little detail beyond the stated commitment to ‘‘denuclearize,’’ a promise that Pyongyang has made and ignored many times. Despite no formal timetable or catalogue of the nation’s nuclear weapons, Trump has repeatedly said he trusts Kim to follow through.
House Speaker Paul Ryan, Republican of Wisconsin, said Trump deserved credit for taking a new approach on a foreign policy challenged that has bedeviled past presidents.
‘‘The status quo was not working with North Korea,’’ Ryan told reporters on Capitol Hill. ‘‘The president should be applauded for disrupting the status quo.’’Material from The New York Times was used in this report.