Administration officials seem to have talked the president out of leaving Syria. They’re right.

President Donald Trump vocally longed for a speedy U.S. withdrawal from Syria. His advisers convinced him otherwise. They have drawn his attention to another mission for the United States in Syria beyond eliminating the Islamic State (ISIS), one focused on another malign actor vying for power there: Iran.

Syria’s nightmare is largely the work of Iran. Bashar al-Assad is responsible for the murder and destruction he’s perpetrated, but Tehran is his enabler: The Iranians have supplied Assad with fighters, weapons, military training, and cash.

The mullahs are bent on dominating the region and building a land bridge that stretches from Tehran to Beirut. Such a bridge would give the them closer proximity to Israel and make it easier to strike the so-called ‘Little Satan’ with the nuclear weapons Iran supposedly wouldn’t dream of building. One can detect Iran’s influence behind Assad’s malignity over the course of Syria’s years-long, bloody civil war. When President Trump described Iranian meddling on September 25, he wasn’t exaggerating. “Iran’s leaders sow chaos, death, and destruction in Syria,” he said at the U.N. General Assembly. “They do not respect their neighbors and borders. Iran’s leaders plunder the nation’s resources to spread mayhem across the Middle East and far beyond.”

Fact check: True.

James Jeffrey, the newly appointed U.S. special representative for Syria, described three objectives for the country in a briefing with reporters last week: the defeat of ISIS, a renewed political process, and “the removal of all Iranian-commanded forces from the entirety of Syria.” Jeffrey said that Trump laid out these goals himself. “As he spelled out,” he said, “the Iranian forces are accelerants to everything that is going wrong in Syria.”

A central question facing the United States is how to use its military power toward these ends. National Security Adviser John Bolton has tied U.S. military presence to the administration’s desire to see Iran out. “We’re not going to leave as long as Iranian troops are outside Iranian borders, and that includes Iranian proxies and militias,” he said in September.

Jeffrey, as well as Defense secretary James Mattis, are more reluctant. Mattis in particular has stressed that the military mission in Syria is legally confined to fighting ISIS. Jeffrey, meanwhile, told reporters that getting Iran out of Syria needn’t “necessarily” involve U.S. boots on the ground. He pointed to diplomatic options as well as local forces we’ve trained in Syria. “For many years, as you know, we had local allies on the ground in northern Iraq and we provided air support,” he said.

Ambiguous rhetoric aside, both Mattis and Jeffrey have joined Bolton in warning against an early U.S. exit from Syria, and they seem to have convinced the president. The Trump administration is squeezing the mullahs financially by re-imposing sanctions that will limit its ability to influence Syria. But sanctions alone won’t do the job. A cash-strapped Tehran is just as likely to see Damascus as its satellite as an enriched one. Possibly more so.

Elsewhere, the United States is reportedly shifting resources away from the Middle East and toward regions proximate to Russia and China. It’s an understandable temptation, but the modest U.S. military presence is one of the only factors preventing Iran from subsuming Syria altogether. If Trump wants to break down Iranian hegemony, the right course in Syria is clear for now: Stay.