The Trump administration is working hard to come up with a comprehensive strategy for Syria after striking the forces of Bashar al-Assad earlier this month. To that end, congressional leaders are preparing a new push to get their old ideas for pressuring the Syrian president, Russia and Iran to the president’s desk.

The administration’s ongoing policy review on how to defeat the Islamic State hasn’t reached a consensus on what to do about the larger Syria conflict. Nobody expected President Trump, who campaigned promising to stay out of Syria, to intervene militarily in his first 100 days in office. Now that Assad’s chemical weapons attack has changed Trump’s mind, his government is committed to playing a more prominent role in solving the civil war.

The Trump administration needs tools to pressure Assad and his partners to engage in real negotiations on the way forward. Simply asking Moscow to abandon Assad without any real leverage is the same strategy the Obama administration pursued unsuccessfully for years. That’s where Congress comes in.

When lawmakers return from their recess next week, they will quickly begin moving several bills designed variously to sanction the Assad, Iranian and Russian governments, several lawmakers and congressional aides told me. Some of the bills are being reframed as ways to try to stop Assad’s atrocities, including one aimed at cutting off support for Iran’s ballistic missile program by House Foreign Affairs Committee leaders Edward R. Royce (R-Calif.) and Eliot L. Engel (D-N.Y.).

(Adriana Usero/The Washington Post)

“This legislation will give the administration much-needed diplomatic and financial leverage to help stop Assad’s slaughter of innocent Syrians,” Royce told me. “It encourages real negotiations by targeting Assad’s backers, Putin and the ayatollah,” referring to Russian President Vladi­mir Putin and Iran’s supreme leader, Ali Khamenei.

The House and Senate, led by Rep. Peter J. Roskam (R-Ill.) and Sen. Marco Rubio (R-Fla.), also each have bills ready to go that would seek to isolate three Iranian commercial airlines, all of which are suspected to be funneling arms and fighters to Assad.

“As the main benefactor of Bashar al-Assad — whose regime has once again used chemical weapons to kill scores of men, women and children — Iran has consistently used commercial aircraft to transport the weapons and troops that have fueled the conflict in Syria which has claimed the lives of nearly 500,000 people,” Rubio and Roskam wrote to Trump on April 10.

Under this legislation, airlines that continue to engage in illicit activities on behalf of terrorist groups or rogue regimes would be placed back on the sanctions list that the Obama administration removed them from after the Iran nuclear deal was signed.

Republican lawmakers also want the Trump administration to cancel licenses that allow U.S. companies such as Boeing to do business with these Iranian airlines. The chief executive of Iran Aseman Air, Hossein Alaei, is a prominent and longtime member of Iran’s Islamic Revolutionary Guard Corps, Rubio and Roskam wrote.

The leaders of the Senate Foreign Relations Committee also have a newly introduced Iran bill that would apply terrorism sanctions to the entire Revolutionary Guard. That legislation was meant to support the Trump administration’s previously announced effort to increase pressure on Iran, but now has new relevance.

Trump’s reversal on Syria makes it much easier for Congress to pass sanctions that had long been opposed by the Obama administration, said Mark Dubowitz, executive director of the Foundation for Defense of Democracies.

“Given that Syria is a front-burner issue now and given the heavy involvement of Iran in Syria, this provides an easy predicate for Congress to move new legislation and for the administration to crack down on Iranian mischief,” he said.

The most directly relevant legislation is the Caesar Syria Civilian Protection Act, a bill that would sanction Assad, Russia and Iran for war crimes and crimes against humanity. The bill is named after the Syrian military photographer who defected with more than 55,000 photos showing the torture and killing of more than 11,000 civilians in custody. The House passed the Caesar bill last year unanimously. Senior congressional aides told me they are prepared to do so again.

There are obstacles to Congress’s emerging strategy. Some Democrats are concerned that sanctioning Iran could put the nuclear deal at risk. There’s no agreement between the House and Senate yet on the way forward. The Trump administration also does not have the staffing or the policy process needed to incorporate Congress’s efforts into a larger diplomatic approach.

“We just don’t have a dancing partner on the administration side,” one senior congressional aide lamented.

Sanctions are only one part of a real Syria strategy. But if the Trump administration is serious about not repeating President Barack Obama’s mistakes in Syria, it will accept the leverage that Congress is offering and use it to compel Syria and its partners to get serious about finding a way to end the slaughter.

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