U.S. Ambassador to the United Nations Nikki Haley and Secretary of State Rex Tillerson on Sunday appeared to offer differing views on the future of Syrian President Bashar al-Assad.

Their comments highlight the degree to which questions remain about the nature of U.S. policy in Syria after President Trump authorized missile strikes against a government air base believed to have been involved in the deployment of chemical weapons against civilians last week.

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.” We don't see a peaceful Syria with Assad in there,” Haley said.

The objective of U.S. policy, she said on NBC's “Meet the Press,” is “to defeat ISIS,” using an acronym for the Islamic State.

“I mean, we've got to do that for peace and stability in the area. It's also to get out the Iranian influence, which we think is causing so much friction and worse issues in the area,” Haley said.

“And then we’ve got to go and make sure that we actually see a leader that will protect his people. And clearly, Assad is not that person,” she added.

But speaking on ABC News' “This Week,” Tillerson said the Syrian people will eventually decide Assad's fate.

Tillerson emphasized the administration's priority in defeating Islamic State forces in Syria and said little about the United States' preference on Assad's future.

“Our priority is first the defeat of ISIS,” Tillerson said. “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.

“In that regard, we are hopeful that we can work with Russia and use their influence to achieve areas of stabilization throughout Syria and create the conditions for a political process through Geneva in which we can engage all of the parties on the way forward, and it is through that political process that we believe the Syrian people will lawfully be able to decide the fate of Bashar al-Assad,” he added.

The apparent dissonance did not go unnoticed. Speaking later on ABC News, Sen. Marco Rubio (R-Fla.) criticized Tillerson for suggesting that the objective of defeating the Islamic State can be achieved as long as Assad remains in power.

“This idea that we’re going to get rid of ISIS and then we’ll hopefully use Assad and others to come up with a solution, it’s not going to work,” Rubio said. “There seems to be a difference between what Ambassador Haley is saying, and what she said last night that Assad really has no future, and what I heard this morning from Secretary Tillerson.

“You cannot have a stable Syria without jihadist elements on the ground with Bashar al-Assad in power,” he added. “They're two sides of the same coin.”

In a separate interview on CBS's Face the Nation, Tillerson said it was the goal of the U.S. and its allies to "navigate a political outcome in which the Syrian people in fact will determine Bashar al-Assad's fate and his legitimacy," citing in part "the United States' own founding principles are self-determination."

Host John Dickerson said critics of that posture have noted that "the Syrian people are in no position to make a determination about the president because he's bombing a lot of them, millions of them have had to flee the country, and he's created a condition where there is no institution that can remove him from power."

"It's important that we keep our priorities straight, and we believe that the first priority is the defeat of ISIS," Tillerson replied. "Once the ISIS threat has been reduced or eliminated, I think we can turn our attention directly to stabilizing the situation in Syria."

Pressed to reconcile that seeming contradiction between the positions advanced by Tillerson and Haley, national security adviser H.R. McMaster suggested in his appearance on “Fox News Sunday” that there was little daylight between the two views.

“What Ambassador Haley pointed out was, it's very difficult to figure out how a political solution could result from the continuation of the Assad regime,” McMaster said. “We're not saying that we are the ones who are going to effect that change. What we're saying is, other countries have to ask themselves some hard questions. Russia should ask themselves … why are we supporting this murderous regime that is committing mass murder of its own population and using the most heinous weapons available.

“While people are really anxious to find inconsistencies in those statements, they are in fact very consistent in terms of what is the ultimate political objective in Syria,” he added.

Pressed by host Chris Wallace to explain Tillerson's statements that destroying the Islamic State is the U.S. priority, McMaster responded, “That's exactly what we're saying.”

“There has to be a degree of simultaneous activity, as well as sequencing the defeat of ISIS first,” McMaster said. “What you have in Syria is a very destructive cycle of violence perpetuated by ISIS, obviously, but also by this regime and their Iranian and Russian sponsors.

“And the resolution of the conflict will entail both of the elements that you're talking about,” he continued.

But the view of Assad's future as articulated by Haley was the one praised by Sen. Lindsey O. Graham (R-S.C.), a frequent critic of the Trump administration.

“Ambassador Haley just said on your program, 'You'll never end the war with Assad in power,'" Graham said. “So that means regime change is now the policy of the Trump administration. That's at least what I've heard.”