UNITED NATIONS — Just after 8 a.m. on Monday, President Trump set off from Trump Tower for his annual week on the diplomatic stage at the United Nations General Assembly. By the time he walked into the General Assembly building 10 minutes later for a session on the illicit global drug trade, domestic politics had already intervened.

Reporters waiting there asked him about the sexual misconduct allegations against his Supreme Court nominee, Judge Brett M. Kavanaugh, which had been published the night before in The New Yorker. Mr. Trump said the tangle of charges brought first by Christine Blasey Ford and now Deborah Ramirez could be one of the “single most unfair, unjust things to happen to a candidate for anything.”

Seizing the opportunity to defend his nominee, Mr. Trump said he stood behind Judge Kavanaugh and dismissed the claims of the two women as “totally political.” Then he walked on into the chamber and spoke to the assembled members about the evils of drug trafficking around the world.

Political tempests often intrude on presidents, whether they are traveling overseas or playing host to foreign leaders at the White House. Still, it is hard to recall a General Assembly that opened against a backdrop of such political turmoil, on so many fronts.