But they also said that, on occasion, Mueller has used the jet to reach a government function and then stayed behind for vacation, returning home aboard a commercial airline that lacks secure communications. Mueller designates his deputy, John Pistole, as acting director when he flies commercially.

Senator Charles E Grassley (Iowa), the senior Republican on the Senate Finance Committee, has expressed concern about the matter. “Using this FBI jet to get to speaking engagements when the plane is intended to help fight terrorism is a good way to lose congressional approval of a necessary resource,” he said. “If the FBI wanted a jet to fly the director around, then it shouldn’t try to justify the plane as a weapon in the war on terror.”