U.S. military, intelligence and law enforcement officials were briefed late last month on a threat against the Pentagon's most senior leaders while they are on American soil, according to five senior U.S. officials with direct knowledge of the matter.

Some officials said the briefings suggested the threat, which remains active, may be potential retaliation for the U.S. military's assassination of Iranian Gen. Qassem Soleimani in January, although the information provided did not draw a definitive link.