New national security adviser H.R. McMaster is already setting a strikingly different tone than his ousted predecessor, Michael Flynn, and President Donald Trump, saying the term "radical Islamic terrorism" isn't helpful for US goals.

At an all-hands meeting of the National Security Council on Thursday, Lt. Gen. H.R. McMaster said jihadist terrorists aren't true to their religion and that the use of the term "radical Islamic terrorism" doesn't help the US in working with allies to defeat terrorist groups, an official present at the session confirmed to CNN.

McMaster also spoke in starkly different terms about Russia, saying the talk about Moscow being a friend of Washington is over, the source said.

WATCH: What to expect from H.R. McMaster as national security advisor

The national security adviser's comments Thursday, which were first reported by The New York Times, and a separate email to all staff on Wednesday have buoyed the low morale at the agency, which has been largely sidelined in recent weeks because of the questions surrounding Flynn's conversations with Russian Ambassador Sergey Kilsyak. The retired lieutenant general resigned last week after admitting he misled Vice President Mike Pence over conversations with the Russian ambassador about US sanctions. Career staff have described the NSC as a dead zone, with little activity while Flynn was in the throes of the controversy.

Flynn's deputy, K.T. McFarland, was present Thursday when McMaster spoke to NSC staff, the source said.

On Friday, during his remarks to the Conservative Political Action Conference in Washington, the President again used the term "radical Islamic terrorists," as he often did on the campaign trail when criticizing President Barack Obama for not saying it.

"So let me state this as clearly as I can, we are going to keep radical Islamic terrorists the hell out of our country," Trump said. "We will not be deterred from this course, and in a matter of days we will be taking brand new action to protect our people and keep America safe. You will see the action."