Of course, many analysts in Washington counsel against a full U.S. troop withdrawal from Syria. They claim that a U.S. troop presence in Syria is the glue holding the anti-ISIS effort together. Yet these analyses frequently ignore the other stakeholders in Syria, all of whom have an interest in managing the ISIS problem. Indeed, because these actors live in close quarters with the approximately 10,000 ISIS fighters who remain in Iraq and Syria, their motivations for continuing the fight are stronger and more compelling.

We are seeing this motivation play out in real time. According to a February 8 Defense Department, Russia and Syrian government forces have escalated military operations against ISIS remnants. The Russians engaged in intense strikes against ISIS positions in the Syrian desert this week. Turkish forces are stepping up raids against ISIS and adopting stricter controls along the Syrian–Turkish border in part to limit the flow of ISIS fighters. In the same report, the Defense Intelligence Agency told the inspector general that Iran “remains committed to countering ISIS by providing lethal aid and advisory support to its partners and proxies in both Iraq and Syria.” It is highly unlikely that all of these operations would cease if President Biden ordered a full U.S. withdrawal from Syria. In fact, one can make the case that the less U.S. military personnel are involved, the more incentive other anti-ISIS actors have to maintain pressure on the organization.