WASHINGTON — The U.S. special forces unit ambushed by Islamic militants in Niger didn’t call for help until an hour into their first contact with the enemy, the top U.S. general said Monday, as he tried to clear up some of the murky details of the assault that killed four American troops and has triggered a nasty political brawl.

Marine Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, told reporters that the American people and the fallen soldiers’ families deserve answers about the deadly ambush in the west African nation. But he said he still lacks many of the details about how the attack unfolded, and he asked for patience as the military investigation continues.

Dunford’s description of the incident, however, underscored how long the mid-morning attack dragged on, and that it was many hours before the wounded and killed were evacuated. He said that “within minutes” after the unit called for assistance, a U.S. drone was moved into position overhead, providing surveillance and full-motion video. He declined to say if it was armed, but said it did not fire.

Another hour went by before French fighter jets arrived, but the wounded weren’t taken out until later in the afternoon when French helicopters arrived along with additional Niger troops. The bodies of the three Green Berets who were killed were evacuated that evening, he said.