SEOUL — As President Trump sat next to Turkish President Recep Tayyip Erdogan in Washington on Wednesday and declared U.S. troops remain in Syria “only for the oil,” his defense secretary, Mark T. Esper, was telling reporters a different story — that leaving hundreds of U.S. troops guarding Syrian oil fields was about fighting the Islamic State. Neither of them has explained exactly what comes next in Syria or how the United States plans to achieve its broader objectives there.

Esper arrived in Seoul on Thursday on the first leg of a four-country Asia tour. He was therefore unavailable to join Trump’s meeting with Erdogan at the White House. Participating in that event were five Republican senators, who criticized Erdogan for — among other things — attacking Kurdish forces who fought alongside U.S. troops for years against the Islamic State and protected a third of Syria from the Assad regime, Russia and Iran.

Although Trump has been widely criticized for abandoning the Kurds, on the plane ride over Esper told reporters the latest plan is to leave “about 500 to 600-ish” troops there — in collaboration with the Kurdish-led Syrian Democratic Forces, whom we are no longer abandoning. Their mission is to stop the Islamic State from taking over the Kurdish-held oil fields in Deir ez-Zor province, he said.

“If [the Islamic State] can generate revenue, then they can pay fighters, they can buy arms, they can conduct operations. They can do all those things because the revenue enables them,” Esper said. “So that’s how the mission relates.”

His explanation makes a certain degree of sense, but it ignores the larger context. It’s much likelier that Syrian President Bashar al-Assad and Iran — not the Islamic State — will take over the oil fields if U.S. troops depart. Invoking the Islamic State is a way to put forth a semi-plausible legal justification for putting U.S. combat troops there.

The real reason U.S. troops are there is different: U.S. officials and lawmakers knew that for Trump, “taking the oil” — to use the president’s language — was the only thing that could persuade him not to withdraw from Syria completely. It’s the only mission Trump cares about. He has said so repeatedly.

“We’re keeping the oil. We have the oil. The oil is secure. We left troops behind, only for the oil,” Trump said Wednesday.

Needless to say, that’s not true. The Kurds “have the oil.” They keep some and sell part of that to the Assad regime, which refines it and sells it back to them. U.S. troops are essentially protecting Assad’s oil. I asked Esper about that.

“I’m not sure how the oil market works in Syria,” he said.

Sen. Lindsey O. Graham (R-S.C.) told me he was working with U.S. oil companies to come in and build new oil infrastructure in the area, to allow the Kurds to export their oil and make more money than now.

Graham was against Trump’s withdrawal of U.S. troops from northeast Syria, but he said he talked to Mazloum Kobane Abdi, the leader of the SDF, who told him the Kurds are thrilled hundreds of U.S. troops are not actually leaving, after all.

Since Trump announced he was withdrawing U.S. troops from Syria for the second time, officials and lawmakers have sought to mitigate the damage and confusion by convincing him to partially backtrack. That effort has now succeeded, for a second time. But damage has been done.

According to Graham, the current state of affairs is “unsustainable.” Stability in northeast Syria depends on Turkey and the Kurds agreeing on an end state near the border both sides can live with, he said.

The Assad regime and its partners are still intent on taking over the rest of Syria, and the U.S. troops who remain are going to come under increased pressure as time goes on. There’s still no clarity on the future of the 200 or so U.S. troops in another southern Syrian base called Tanf, or the fate of the thousands of innocent civilians living nearby in a camp called Rukban.

This week, the State Department is hosting a meeting of the coalition to defeat the Islamic State and a meeting of the “Small Group of Syria,” which includes European countries we are asking to deploy troops. But these countries won’t do that while our president is publicly declaring we are there “only for the oil.”

Russian forces are now patrolling alongside the forces of our NATO ally Turkey. Our Kurdish partners are in a public alliance with the Assad regime, one that we forced them into seeking. Our acquiescence to Turkey’s invasion has resulted in only more bloodshed and instability. Iranian influence in Syria is higher than ever.

Trump and his officials need to get on the same page. They need to figure out a strategy to use our very limited leverage to best achieve our objectives and interests, and they need to tell the American people and the world what it is — before the situation in Syria gets even worse.

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