Last week, I wrote about one of the troublesome byproducts of the Trump-Putin summit in Hamburg: a ceasefire in southwestern Syria that Israel worries will entrench Iranian control of that area bordering the Israeli Golan Heights. The day after my article came out, the Washington Post reported on another troubling decision that President Trump has made vis a vis Syria: Ending a CIA program that had provided arms and training to anti-Assad forces.

Gen. Tony Thomas, commander of U.S. Special Operations Command, insisted that this decision was not a sop to Russia. But whether intended that way or not, that is the effect of this decision. The Post quoted a current U.S. official as saying: “This is a momentous decision. Putin won in Syria.” That seems indisputable. By stopping support for the anti-Assad forces, the U.S. is conceding that Bashar Assad—Russia and Iran’s client—will stay in power indefinitely.

The U.S. continues, of course, to support the Syrian Democratic Forces, the misleading name of the largely Kurdish YPG rebels that are besieging the Islamic State city of Raqqa. But the YPG has no interest in overthrowing Assad and no interest in governing Arab areas. Their objective is to set up a Kurdish state, Rojava, in northern Syria, and they have friendly relations both with Damascus and Tehran. There is no way that the Kurds can rule the majority of Syrian territory, which is populated by Arabs.

That will leave multiple factions to battle it out for control of most of Syria: the Iran-Assad-Russia axis (spearheaded by Hezbollah and other Iranian-created militias, and backed by Russian air power), the al-Nusra Front (the al-Qaeda affiliate in Syria, which is rumored to get support from Gulf states), and the Islamic State, which may be down at the moment but hardly out. These factions have their differences, but they are united on certain core essentials. All are rabidly anti-American, anti-Western, and anti-Israeli, and all are violent jihadists, whether of the Shiite or Sunni persuasion.

It is not in America’s interest for any of these groups to control a substantial amount of Syrian territory. Yet President Trump has now made the puzzling decision to stop support for the only faction that could keep substantial swathes of Syria out of jihadist hands.

Granted, the moderates loosely affiliated with the Free Syrian Army have been losing ground for years. That is largely the fault of President Barack Obama, who unwisely refused to heed the advice of the officials in his administration who advocated a vigorous train-and-assist program for non-jihadist rebels. Such a program would have had a much greater chance of working in earlier years. America’s failure to help the moderates has led many fighters to defect to more radical groups, and many of our allies have been killed or expelled.

But it would not be impossible to reverse these trends, and trying would be worthwhile. There are, after all, scores of military-age Syrian men who have fled the country as refugees. If the U.S. had the will to act, they could be trained, armed, and organized into an effective military force on Jordanian or Turkish soil and then sent with U.S. advisers and U.S. air support to secure Syrian territory. We currently provide that kind of aid to the Kurds, but we have cut off the Arab fighters, who are willing to risk their lives to fight against one of the biggest war criminals in the world—Bashar Assad, who is responsible for upwards of 400,000 deaths.

This decision makes little sense on strategic or moral grounds. Instead of abandoning the moderates, we should be doing more to buttress them. Even if it’s too late to overthrow Assad, who is more secure than ever since Russia entered the conflict in 2015, it might at least be possible to limit him to a few major cities and the Alawite heartland and prevent jihadists from taking control of most of the Syrian countryside. If we stop trying, we are conceding much of Syria to the Iran-Russia camp indefinitely. That is not in our interest, nor in that of our regional allies. Vladimir Putin, on the other hand, will be very happy.