When Obama began this program, he conceived of it in narrow terms; he never sought to overthrow or even seriously weaken the Assad regime. Rather, he aimed to apply just enough pressure to convince him to accept a political solution, but not enough to risk the regime’s stability (which would presumably leave the United States to fix post-war Syria). It is noteworthy that this reflected U.S. policy at its peak levels of confidence and belligerence against Assad. When Iran and especially Russia entered the war, the Obama administration understood that pressuring Assad would require escalating the covert rebel program. Obama had no appetite for such an escalation: He knew the risks it entailed, including possible conflict with Russia.

Indeed, the opposite occurred. Russia’s intervention led to an agreement with Jordan, which, with its knowledge of rebel groups across its border, played a central role in supporting the insurgents. Russia agreed to c urb fighting in southern Syria, where the U.S.-backed rebels have been most successful. Rebels were instead pressured to fight extremist groups only. Meanwhile, U.S.-backed rebels in northern Syria were overwhelmed by Islamist groups that either destroyed or coopted them, rendering the U.S. role there meaningless. In 2017, U.S.-backed groups have sporadically fought the regime, albeit from a weaker position and with far less support from Washington.

Thus, by the time of Trump’s inauguration, the U.S. covert program, which was never particularly bold to start with, was already a shadow of its former self. For his part, Trump had already made clear he was unenthusiastic about it. In November 2016, he told the Wall Street Journal he was likely to end support for the Syrian rebels, claiming, “We have no idea who these people are,” and suggesting that the United Sta tes should focus instead on the Islamic State. Although Trump insisted this vision was the opposite of Obama’s, the latter always shared and expressed these views, even as the intelligence community was conducting its proxy war against Assad.

There is a subtle difference between the two presidents’ views, but they concern Russia rather than the covert program itself or America’s goals in Syria. Trump seems to believe that Russia can end the violence in Syria; by contrast, the Obama administration approached the Russia option with mild and jaded desperation, having eliminated other policy alternatives for ending the war. Trump’s confidence is likely what pushed him to end support for the rebels who could, after all, have been left on “life support” or held in reserve.

Without U.S. support, the rebels cannot survive continued war against the Assad regime and its allies. This places the fate of opposition-held southern Syria—one of the last areas controlled by nationalist, mainstream groups close to the United States—at the mercy of Russia, which has committed to enforcing a ceasefire there. Even if Russia wanted to force the regime and Iran to respect a ceasefire, Syria belongs to factions who control the ground, which means the Assad regime and Iran-controlled fighters. They will eventually move on southern Syria when the United States grows bored with the problem, post-ISIS, and Russia capitalizes on its display of parity with the United States. A paranoid police state will not tolerate a rebel “cancer” so close to Damascus that might later metastasize into a serious security threat. As for the north, already-outmatched, U.S.- backed insurgents have effectively lost already.