Lawmakers on Capitol Hill want the Trump administration to outline a broader strategy in Syria following the president's decision to authorize U.S. missile strikes Thursday night in response to the apparent chemical weapons attack by Syrian President Bashar Assad.

"I think it was appropriate but I would like to say, despite all the enthusiasm we see this morning, if I might quote [Winston] Churchill, 'It's the end of the beginning, not the beginning of the end,' " Senate Armed Services Chairman John McCain, R-Ariz., told MSNBC on Friday morning.

He added: "We have a Middle East in chaos, the Europeans being destabilized, the spread of [the Islamic State] throughout the world. This is the challenge of Bashar al-Assad, and then we have also got the challenge of ISIS, so there's a lot more to go."

Speaking on the Senate floor, Majority Leader Mitch McConnell, R.-Ky., urged the administration to collaborate, and elaborate, on where the strategy goes from here. "In the days ahead, I am committed to working with the administration to continue developing a counter-ISIL strategy that hastens the defeat of ISIL and establishes objectives for dealing with the Assad regime in a manner that preserves the institutions of government in an effort to prevent a failed state," he said.

"Making sure Assad knows that when he commits such despicable atrocities he will pay a price is the right thing to do," Senate Minority Leader Chuck Schumer, D-N.Y., said late Thursday. "It is incumbent on the Trump administration to come up with a strategy and consult with Congress before implementing it."

Senators were scheduled to hold a classified briefing with military and intelligence officials Friday afternoon. The Senate adjourns Friday afternoon for the two-week Spring recess; the House has already left town for the break.

Questions about constitutionality

Some Democrats, and at least two Republicans, are questioning the strikes' constitutionality. The military action also is reviving debate over Congress' role in the matter and whether the president needs to obtain congressional authorization for any prolonged military engagement in the region.

Sen. Rand Paul, R-Ky., who favors a more isolationist foreign policy approach, wrote on Twitter, "The President needs Congressional authorization for military action as required by the Constitution."

Rep. Justin Amash, R-Mich., echoed Paul's remarks: "Airstrikes are an act of war. Atrocities in Syria cannot justify departure from Constitution, which vests in Congress power to commence war."

That notion is supported by Rep. Barbara Lee, D-Calif. — a prominent liberal supporter of Congress passing a new authorization for the use of military force (AUMF). On Twitter, Lee characterized the airstrikes as "an act of war."

Lee tweeted: "I was the lone vote against 2001 AUMF. Syria strikes are far beyond the scope of this war authorization. Speaker Ryan needs to bring a vote."

President Trump — like President Barack Obama before him — has launched airstrikes against ISIS targets using as legal justification the 2001 war authorization Congress passed after the attacks of Sept. 11, 2001. But lawmakers are split over whether that justification covers attacks against the Assad government.

House Speaker Paul Ryan, R-Wis., said the strike was "appropriate and just" and signaled that he also wants the Trump administration to consult Capitol Hill lawmakers on the matter. "I look forward to the administration further engaging Congress in this effort," he said.

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KELLY MCEVERS, HOST:

We start this hour with reaction to President Trump's decision to launch airstrikes on a Syrian airbase. That happened last night in response to an apparent chemical weapons attack by Syrian President Bashar al-Assad on civilians.

First to Congress where members are generally supportive, but they say they want more answers about the Trump administration's broader strategy in Syria and whether that will require Congress to weigh in. NPR congressional reporter Geoff Bennett has more from Capitol Hill.

GEOFF BENNETT, BYLINE: There were strong words of support today from the top Republican in the Senate, Mitch McConnell.

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MITCH MCCONNELL: I very much approve of what the president did. I think it was not only an important message to Assad but to everybody else who may be wondering just what this new administration is going to be like.

BENNETT: Lawmakers in both parties largely approve of the strikes, including Senate Minority Leader Chuck Schumer.

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CHUCK SCHUMER: Making sure that Assad knows when he commits such despicable atrocities, he will pay a price, is the right thing to do.

BENNETT: But in the hallways outside the upper chamber, some senators questioned the legality of the airstrikes.

CHRIS MURPHY: This certainly was not a lawful act.

BENNETT: That's Democratic Senator Chris Murphy of Connecticut.

MURPHY: And if the president gets away with taking this action against the Syrian regime without a congressional vote, there is no end to the executive power over military affairs. If you don't need authorization to strike a foreign government with no imminent threat to the United States, then when will Congress ever have to weigh in on military action overseas? I think this is a turning-point moment for the role of Congress in setting foreign affairs.

BENNETT: As Murphy's comments make clear, Trump's decision is reviving a debate over whether the president needs to get congressional authorization for military action in the region. President Trump, like President Barack Obama before him, launched airstrikes against ISIS targets using legal justification from 2001.

Congress passed a war authorization after the September 11 attacks, and lawmakers are split over whether that covers U.S. military action against the Assad government. Democratic Senator Tim Kaine of Virginia says it doesn't. He's a longtime advocate for passing a new war bill.

TIM KAINE: The Constitution that we all pledge an oath is very, very plain that except for defending the nation against eminent attack, you can't start a war without an act of Congress.

BENNETT: But Mitch McConnell and other top Republicans say Trump was well within his rights as commander in chief to launch the airstrikes which they describe as limited and tactical. Republican Senator John McCain of Arizona says he would encourage the president to launch more airstrikes against Syria without congressional approval.

JOHN MCCAIN: To stop the slaughter of innocent men, women and children. And anybody who says that he shouldn't stop the slaughter if he can of innocent men, women and children is not deserving of my respect or the respect of the American people.

BENNETT: The issue is sure to be among the many Congress faces when members of the House and Senate return to Washington in two weeks following their spring recess.