When Wallace asked what the United States will do if Russia defends its interests in Syria, mentioning Russian Prime Minister Dmitry Medvedev's comments Friday that the USA missile strike in Syria put the two countries "on the verge of a military clash", McMaster stood firm on his position that Russia is "part of the problem" and should become "part of the solution". In no way do we see peace in that area with Russian Federation covering up for Assad.

"What we're saying is, other countries have to ask themselves some hard questions", McMaster said in an interview on "Fox News Sunday".

Air strikes have continued unabated since the USA attack on Friday. "And so what we're trying to do is obviously defeat ISIS".

"I think, as you saw with the strike, that there has to be a degree of simultaneous activity as well as sequencing of the defeat of ISIS first", McMaster said. "And clearly, Assad is not that person".

"If Russia wants to be absolved of responsibility for future attacks, Vladimir Putin needs to enforce commitments, to dismantle Assad's chemical weapons arsenal for good, and to get fully engaged with the United Nations peacekeeping progress".

"I've never been more encouraged by the Trump administration than I am today", the senator said.

McMaster told Fox News Sunday host Chris Wallace the "president acted decisively" and that while the strike wasn't meant to take out all of Syria's capabilities, "it was a strong signal that the US will not stand idly by".

But for Russian Federation or any other nation, McMaster said, supporting Syria's regime isn't in its best interest, and Russian Federation ultimately decides the kind of relationship it wants with the United States. "I don't think there is a strategic shift". I think we ought to ask them a question. Russia's not going to have your back anymore. "And if they do, we're going to make sure that both of you know that we're not going to settle for it'".

"Do they want it to be a relationship of competition and potential conflict", McMaster said.

"I think that's dependent on the actors that are at play". "Once we can eliminate the battle against ISIS, conclude that and it is going quite well, then we hope to turn our attention to cease fire agreements between the regime and opposition forces". He questioned the wisdom of backing rebels, suggested that Washington should work more closely with Russian Federation to fight Islamic State, and noted that while he didn't like him, "Assad is killing ISIS".

"Our priority in Syria ... really hasn't changed".

WALLACE: Let me bring in - you mentioned Russian Federation.

The Syrian opposition, which long accused the Obama administration of inaction, wants the USA attack to be the start of a more aggressive policy towards Assad.

Moscow called the US airstrike an "act of aggression" and an "egregious and obvious violation of global law that can not be justified". "The first priority for them was to cover for Assad".

Others were more hesitant to strike a new tone, despite Trump's decision to strike a Syrian airfield used by Assad.

"Haley indicated in an interview on CNN's "State of the Union" that the United States does not see a peaceful political resolution for Syria's civil war as long as Assad remains in power".

The contradictory sentiments garnered criticism from top lawmakers, who were left to infer which policymaker represented the president's thinking.

Sen. Lindsey Graham (R-SC) did not mince words - or letters - when he remarked on Bashar al-Assad's flippant attitude toward President Trump on Sunday's "Meet the Press".