The White House said he would depart aboard an older presidential 747 before returning through Britain to Washington on his new plane. Mr. Trump boarded the older plane from the left-side door in view of cameras, and news organizations, including The New York Times, reported that he had traveled on it to Britain, where he switched back to the newer plane. The operation was seemingly devised within hours after Trump was personally briefed on the danger. Trump had boarded the older modified 747 from its left-side door in view of cameras, while reporters hurried aboard through lower steps at the rear. Reporters and some White House staff continued aboard Air Force One without being told Trump was elsewhere, becoming unwitting decoys.