After President Donald Trump was mostly cheered by the international community for his missile strikes targeted at the Syrian government, he must now grapple with how to pair his first use of decisive military force with a strategy to contest a six-year-old war that has challenged the world.

U.S. officials described Trump’s sudden decision to launch 59 Tomahawk cruise missiles against a Syrian air base as a targeted retaliation on the source of a suspected deadly attack on civilians that occurred two days before—and a symbolic show of American power.

But foreign policy experts say that Trump, by inserting himself squarely into a complex battlefield, will have to deal with the aftermath, and decide how he wants to handle the dual challenges of fighting ISIS, and responding to Syria’s dictator leader Bashar Assad, whose brutality many blame for inflaming terrorism in the region.

“Last night’s strikes were an act of war. We need to be clear about that,” said Jonathan Schanzer, a scholar in Middle Eastern studies and vice president at the Foundation for Defense of Democracies, in an interview with The Daily Signal. “The intent here and messaging has been, this was a contained, commensurate response and that’s where this ends.”

“But the question is whether the Russians, Iranians, and Syrians continue to test America’s patience,” he added. “I don’t put it past that axis to continue the atrocities in Syria. The Syrian war certainly has now grabbed the attention of the president, so I wouldn’t rule out future strikes.”

‘Mobilize a Common Strategy’

During the campaign, Trump emphasized his focus in Syria would be on defeating ISIS, the terrorist group that maintains its base in that country, and in the early weeks of his administration, the White House articulated that facilitating the removal of Assad from power was not a priority.

This week, Trump’s calculus seemed to change when the president said the chemical weapons attack had “crossed a lot of lines for me” and that his attitude toward “Syria and Assad has changed very much.”

H.R. McMaster, Trump’s national security adviser, said Thursday night that he hoped the U.S. strikes on the Syrian government’s infrastructure would “shift Assad’s calculus,” because this was the first time America had taken direct military action against the dictator’s regime.

President Barack Obama had feared being dragged deeper into a civil war that has killed nearly 400,000 people and displaced half the country. He refused to strike Assad’s government after a similar chemical weapons attack in 2013 despite issuing a “red line” that created expectations for military force.

Trump’s action, some experts say, could provide leverage against Assad that the previous administration never had.

“The cruise missile strike sends a strong signal that Assad cannot act with impunity and use chemical weapons,” said Jim Phillips, a Middle East expert at The Heritage Foundation. “It undermines his perceived power and is a powerful warning shot that will constrain his future options. It is crucial to follow up the strike with aggressive and focused diplomacy to mobilize allies behind a common strategy in Syria.”

Yet the the situation on the ground in Syria has changed dramatically since 2013, with Russian troops intermingled among Syrian forces as part of Moscow’s push to keep Assad in power.

“This strike comes four years from when we should have taken another strike in a similar way,” said Brian Katulis, a senior fellow for national security at the Center for American Progress, in an interview with The Daily Signal. “Now, there is more uncertainty and instability. You don’t want to escalate things and inadvertently kill Russian troops. The chances of retaliation or blowback today are much greater.”

Dealing With Russia

Next week, Secretary of State Rex Tillerson will meet with President Vladimir Putin of Russia, who, along with Iran and Hezbollah, the U.S.-declared Shia terrorist group, has propped up Assad’s government and provided military support to it.

“We have not really seen the affect of U.S. power on the Russian calculus for the last six years or longer,” Schanzer said. “The previous administration was very circumspect with applying power. The Russians took that as a green light to engage in destabilizing activities in Syria and Ukraine. Whether Trump’s new action has a deterrent effect will be interesting to see.”

Russia’s immediate reaction to Trump’s decision has been to not back down. Dmitry Peskov, a Putin spokesman, told reporters the Russian president “considers the American strikes against Syria an aggression against a sovereign government in violations of the norms of international law, and under a far-fetched pretext.”

The Russian government said it was pulling out of an agreement to minimize the risk of in-flight incidents between U.S. and Russian aircraft operating in Syria.

U.S. military officials later insisted Russia was continuing to comply with the agreement.

Russia’s early rhetoric concerns experts about the possibility of a direct military confrontation with Moscow, which has air defense systems in Syria that can shoot down U.S. aircraft. This could complicate the fight against ISIS, since the U.S.-led coalition until now has been conducting airstrikes mostly without interference from Russia and the Assad government.

“Trump’s decision to strike in Syria only improves the U.S. leverage against Assad and Russia to a limited extent,” said Michael O’Hanlon, director of research for the foreign policy program at the Brookings Institution, in an interview with The Daily Signal. “Russia will call our bluff. If we really want them to believe we will dramatically increase our military role in Syria, they know we aren’t serious. I don’t think that’s something Trump wants to do, and I wouldn’t advise it either. As much as I want the war to end, I am not sure I want to risk a U.S.-Russia conflict to do it.”

But James Jeffrey, a deputy national security adviser to President George W. Bush, predicts Russia will increasingly feel isolated because of Trump’s action. Peskov, the Putin spokesman, recently said Moscow’s support for Assad “is not unconditional” and Jeffrey says the international condemnation of the chemical attack could frustrate Russia enough to change its calculus.

“We amassed support from around world for these strikes,” Jeffrey told The Daily Signal in an interview. “That’s something the Russians have to consider. They want to isolate the U.S. and Western world, and that’s not something Russia has now. Putin is outgunned against the U.S. coalition, and isolated internationally. If Trump gives him some way out of Syria through a diplomatic process, why wouldn’t Putin take that?”

‘Has to Stop’

Still, the experts say the Trump administration should proceed cautiously in how aggressively it presses Assad, who remains determined and capable.

Phillips notes that Trump’s strikes only targeted one airfield, not Syria’s air force or chemical weapons capabilities, and he warns there is little the U.S. can do to stop Assad’s security forces from continuing the war, short of taking more military action.

“It would be a mistake to expand the military effort to include the goal of removing Assad,” Phillips said. “That would be a costly and risky mission creep that would entail military clashes with Russia and Iran. And it would bog down the U.S. military in an open-ended effort to stand up and stabilize a post-Assad government. Pressing Assad to step down as part of a political settlement should be a long-term diplomatic goal pursued through sanctions, but ISIS and al-Qaeda should remain the chief targets for U.S. military action in Syria.”

Max Abrahms, a terrorism expert at Northeastern University, is concerned that pushing for the removal of Assad could leave a power gap and make the country even more of a haven for Islamic extremists.

“I worry by weakening the Syrian government’s position, this will help to breathe new life into the al-Qaeda-allied rebels,” Abrahms told The Daily Signal in an interview. “I don’t think Trump wants to get involved into the domestic politics of this country. It will absolutely consume his presidency.”

Even if the Trump administration keeps its word about the limited intent of its missile attack, the experts agree the president has sent a political message that the U.S. can use to its advantage by demonstrating the use of force is on the table.

“This is not George W. Bush going to Iraq in 2003,” Jeffrey said. “There is no doubt in my mind Trump won’t use force to drive Assad out. But he can use military force as part of a diplomatic strategy to get an agreement between Assad and the Sunni majority of his population who he is trying to bomb out of existence. That has to stop and it started stopping yesterday.”