The Pentagon confirmed Thursday that a second U.S. Special Operations team was in the area when a Special Forces team was ambushed in Niger earlier this month.
"There are other teams that operate in Niger," Lt. Gen. Kenneth F. McKenzie, Jr., director of the Joint Staff, told reporters. "There was one that had something to do with this operation but I am not going to be able to give you any more specific details about what happened."
When asked if the second team was involved in the attack, McKenzie answered, "It's involved in the timeline."
The Chairman of the Joint Chiefs of Staff, Gen. Joe Dunford, said earlier this week that the 12-man Special Forces team was ambushed by 50 heavily armed ISIS-affiliated fighters while conducting a "reconnaissance mission."
Four U.S. soldiers died in the fighting, while two others were wounded. One of the fallen soldiers, Sgt. La David Johnson, 25, was unaccounted for two days after the ambush before his body was discovered by allied Nigerien forces.
On Capitol Hill, Sen. John McCain, R-Ariz., the chairman of the Senate Armed Services Committee, said a classified briefing about the ambush conducted by two senior Pentagon officials shed light on in a number of areas. But McCain, who had threatened a subpoena to get information, said other key questions remain unanswered.
McCain said he wanted to know why it took so long to recover Sgt. Johnson's body. He said Pentagon officials covered the matter but he indicated they didn't know everything yet.
"I had a lot of questions. All of us had questions," he said.
McCain responded testily when asked if the early October mission that led to the deaths of the American troops in Niger was a failure.
"Do you think there's a failure if four Americans are killed?" he said.
Asked if the result was bad luck or bad strategy, McCain answered: "Both."
Officials believe the militants were tipped off to the presence of U.S. forces after a meeting with local tribal elders in Niger ran longer than expected.
The Associated Press contributed to this report.