A diplomatic standoff over restoring international sanctions against Iran may be the most vivid example yet of how the United States has largely isolated itself from the world order — instead of isolating Tehran, as the Trump administration intended. At nearly every step President Trump has taken in his dogged pursuit to demolish a 2015 accord limiting Iran’s nuclear program, he has run into opposition, including from America’s strongest allies in Europe. On Thursday, the opposition turned into open defiance.

Secretary of State Mike Pompeo traveled to New York to personally demand that the United Nations Security Council “snap back” the sanctions on Iran for violating some terms of the nuclear deal. The act was born of frustration: His closest allies had rejected an American effort to recast the terms of the deal by extending an arms embargo against Iran that begins to expire in October. Only the Dominican Republic voted with the United States.

Mr. Pompeo, sounding incredulous, again accused Iran of fomenting terrorism, destabilizing the Middle East and trying to hide its nuclear and weapons programs from international inspectors. But he directed some of his harshest words toward diplomats from Britain, France and Germany, whom he said “chose to side with ayatollahs.”