• President Trump said he would announce today whether the U.S. would remain part of the Paris climate agreement, an issue that has split his administration.

An American withdrawal would severely weaken the accord, which commits nearly every nation to taking action to slow global warming. Mr. Trump has said that carbon regulations would hurt the U.S. economy. But he is also known for last-minute reversals.

Jean-Claude Juncker, the president of the European Commission, suggested Mr. Trump did not understand the mechanics of the treaty. “Not everything written in international agreements is fake news,” he said.