Not many people are paying attention, but President Trump’s meeting Monday with Russian President Vladimir Putin will determine the future course of U.S. policy on Syria. There’s still time to avoid the most dangerous outcomes. Trump must not strike a catastrophically bad deal that would only worsen conditions for the Syrian people, the region and the United States’ security.

Ahead of the summit, Trump’s national security team has been battling internally over a proposed deal that Trump discussed with Jordan’s King Abdullah II in Washington last month. It would fulfill Trump’s wish to withdraw most U.S. troops from Syria “very soon ” while endorsing Syrian President Bashar al-Assad’s and Russia’s brutal takeover of southern Syria, a direct violation of Putin’s last deal with the Trump administration.

Russia, in turn, would promise to limit the Iranian presence near Syria’s borders with Jordan and Israel. The deal would also encourage the U.S.-backed, mostly Kurdish Syrian Democratic Forces to work with Assad and Russia as Trump removes the 2,200 U.S. troops in Syria’s northeast. Jordan and Israel seem to be on board. But inside Trump’s team, there’s a split.

Pushing the proposal are Brett McGurk, the State Department’s envoy to the global anti-Islamic State coalition, and David Satterfield, the acting assistant secretary of state for near Eastern affairs, who is rumored to be Trump’s pick for ambassador to Turkey, according to two U.S. officials. Other State Department, Pentagon and National Security Council officials are deeply skeptical of the potential arrangement.

National security adviser John Bolton internally objected to at least two aspects of the deal, the officials said. First, he insisted the small U.S. military base near the al-Tanf border crossing not be traded away as part of the negotiation. Bolton also argued that any deal must result in Iran’s full, not partial, withdrawal from Syria.

Military officials worry the deal would leave the fight against the Islamic State unfinished, allowing their resurgence in a repeat of what happened after President Barack Obama withdrew U.S. troops from Iraq in 2011. Lt. Gen. Michael Nagata, a top official at the National Counterterrorism Center, said this week that the Islamic State remains in Iraq and Syria and the fight is not over.

“My view is the role of the United States is irreplaceable in dealing with what remains,” he said.

The deal’s basic premise is that reducing violence in Syria is the first priority, allowing refugees to return and a political process to emerge. It’s based on two false assumptions about Russia: that Moscow seeks a genuine negotiated political solution and has the power or will to contain Iran.

Secretary of State Mike Pompeo testified last month that Russia’s capacity to push Iran out of Syria is an “open-ended question.” He also said U.S. efforts to push a diplomatic solution are hampered by a lack of pressure on Assad and his partners.

“We are not yet in a position where we have sufficient leverage to achieve the political outcome that is in the best interest of the United States and the world,” Pompeo said.

By announcing withdrawal as his primary goal, Trump weakened U.S. leverage and undermined his own negotiators. Trump has also frozen almost all the U.S. humanitarian assistance in Syria and cut off aid to the rebels, additional unilateral concessions to Assad, Russia and Iran.

Nobody knows what Trump and Putin will agree to in Helsinki. It could be a loose agreement to pursue the proposed deal in the weeks ahead. That means the policy fight begins in earnest when the summit ends. But whatever the leaders say will loom large over those discussions.

Congress is trying to give Trump leverage he probably won’t use. The House has already passed multiple bills that would heavily sanction the Assad regime and any partners who assist its ongoing mass atrocities. One bill is named after “Caesar,” the Syrian military defector who smuggled out roughly 55,000 images documenting the regime’s torture and murder of thousands of civilians in custody.

“What message is the world sending? It’s okay for the Russian Air Force to bomb hospitals?” Caesar asked me during his recent visit to Washington. “Where is humanity?”

The United States still has a role to play in Syria and a responsibility to do what’s right and safe. The administration at least must hold on to its last bits of leverage to push for the opposition’s inclusion in real negotiations, humanitarian access for the starving, an end to Assad’s atrocities and accountability for the war criminals. Nothing Putin agrees to can be trusted, so if the deal is to trade U.S. troop withdrawal for Iranian troop withdrawal, Iran has to withdraw its troops first.

Helsinki is not a peace conference ending a war. It is a way station on the path to the war’s next phase. Assad’s brutal slaughter will only increase as the United States withdraws. Unless Trump negotiates tough with Putin now, he could see the Islamic State return and Iran expand — on his watch and with no one else to blame.

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