 -- After meeting separately with Secretary of Defense James Mattis, both Sens. Lindsey Graham and John McCain said the military should do more to keep members of Congress aware of its counterterrorism operations around the world.

Sen. Graham told reporters that one of the open questions surrounding the ambush in Niger, which killed four Americans, is whether it was the result of an intelligence failure.

“It’s too early to say. That’s exactly the questions we should be asking ourselves. In war you fail, you make mistakes and the whole goal is to learn from your mistakes and not repeat them.”

Graham said Sen. McCain will likely hold a hearing on the operation, and the strategy more broadly, next week. A spokeswoman for the Senate Armed Services Committee did not comment.

Graham also said the military will likely change its rules of engagement in Africa, and anywhere else they need to be changed, so that forces can hit targets based on their status – for example, a member of the Taliban or ISIS – versus their conduct.

That will likely prompt a debate in Congress over the broader counterterrorism strategy and the need for an updated Authorization for the Use of Military Force or "AUMF" – a debate which certain members have called for repeatedly over the years but which has largely been stagnant.

Mattis and Secretary of State Rex Tillerson will testify at a Senate Foreign Relations Committee hearing on the current AUMF next week.

“The many questions surrounding the death of American servicemembers in Niger show the urgent need to have a public discussion about the current extent of our military operations around the world,” Sen. Tim Kaine, a longtime proponent of an updated AUMF, said in a statement.

The counterterrorism fight is going to shift to Africa more and more, Graham said.

“You're going to see more actions in Africa, not less. You’re going to see more aggression by the United States towards our enemies, not less. You're going to have decisions being made not at the White House but in the field. And I support that entire construct.”

McCain met separately with Mattis, and after the meeting, with the secretary at his side, McCain said he and Mattis talked about the need for his committee to receive more information about the Niger ambush.

"I felt that we were not getting sufficient amount of information and we are clearing a lot of that up," McCain said.

Mattis added, "We can do better at communication. We can always improve on communication and that's exactly what we'll do.

Ahead of his meeting with McCain, Mattis was asked if the threat of the subpoena prompted him to meet with the senator. "Are you kidding me?" Mattis said to the reporter.

Mattis said the president is "kept fully informed' on the Niger ambush, but declined to say how often he is briefed about the timeline.