Syrians walk down a street past rubble from destroyed buildings. (Hamza Al-Ajweh/AFP/Getty Images)

Bashar al-Assad’s ongoing assault on the Damascus suburb of Eastern Ghouta is a war crime that has already killed more than 900 civilians. But while it’s easy to condemn this “brutal campaign,” as the White House has dutifully done, it’s hard to know what to do about it. A U.N.-brokered cease-fire is being predictably ignored. A small humanitarian relief convoy finally made it through, but its arrival will not stop the slaughter.

In 2012, I joined many others in calling for the United States to enforce a no-fly zone to stop the rain of Assad’s barbaric “barrel bombs” and to provide aid to the Free Syrian Army to overthrow him. A lot more people might be alive today if President Barack Obama had listened, and a strategic and humanitarian disaster might have been averted. But, although right six years ago, I no longer think that advice makes sense now. Russia got involved in Syria in 2015, and the United States can’t attack Russian aircraft without risking a war. Thanks to Russian and Iranian aid, Assad is no longer on the verge of defeat. His position is more secure than ever, and it’s only a matter of time before he reconquers most of Syria.

Using U.S. airpower to aid the embattled people of Ghouta might make us feel good, but it would not save lives. Even if we could ground Russian aircraft — a big if — pro-regime forces would simply use artillery and multiple-launch rocket systems to pulverize the city. U.S. intervention would only prolong the agony. 

The way to save lives, I’ve sadly concluded, is to let Assad win as quickly as possible. Aleppo was a charnel house in 2016. But now that it has fallen to Assad’s forces, pictures are circulating of civilians strolling through its rebuilt public park. It’s terrible that they have to live under Assad, but at least they’re alive. Tyranny is preferable to endless and useless war.

I once would have been sympathetic to the plan put forward by American Enterprise Institute fellow Kenneth Pollack to aid Syrian rebel groups to bleed the Iranians and Russians. No longer. Such aid makes sense when, as in Afghanistan in the 1980s, the rebels have a realistic chance to prevail. It’s not right, however, to use Syrians as cannon fodder in a great power rivalry when they have no hope of winning.  

That’s not to suggest that there is nothing the United States can do. We can try to bargain with Moscow to restrain Assad’s brutality in return for an end to U.S. opposition to his regime, and we can maintain the taboo against the use of weapons of mass destruction. In April, President Trump launched cruise missiles against a Syrian airfield in response to a sarin-gas attack by Assad’s forces. This year, there have been at least seven reports of Assad using chlorine gas. Trump should launch airstrikes against the responsible Syrian units — as he is reportedly considering — even though it would do little to ameliorate the larger horrors of the conflict.  

The most important thing the United States can do now is to stand with our Kurdish and Arab partners in the Syrian Democratic Forces that liberated northeastern Syria from the Islamic State. The Kurds control about 25 percent of Syria’s territory, and there is a U.S. military presence 2,000 strong to aid them and prevent the Islamic State from returning. The Turkish government is not happy about this. President Recep Tayyip Erdogan has sent the Turkish army, working with Syrian allies, to attack the Kurdish-held town of Afrin in northwestern Syria. Erdogan sees no difference between the Syrian Kurds in the YPG (People’s Protection Units) and the Turkish Kurds in the PKK (Kurdistan Workers’ Party), whom he has long regarded as domestic subversives and mortal enemies.

Trump should cut a deal with Erdogan: The YPG will sever all support for the PKK in return for the Turks pulling back. As long as the YPG sticks to this bargain, the United States will use its airpower and advisers to defend the Syrian Kurdish enclave east of the Euphrates River, just as it committed after the 1991 Gulf War to defend the Iraqi Kurds. Turkey wasn’t happy with that decision but has learned that it can live with, and happily trade with, the Kurdish Regional Government. 

Leaving Assad in control of three-quarters of Syria will be a bitter pill to swallow. He is not only a war criminal but also a threat to Israel — as long as Assad remains in charge, Iran will attempt to establish military bases in Syria. But Israel can defend itself, and we missed our best opportunity under Obama to oust Assad. Now we have no choice but to accept the grim reality — Assad is going to win — while trying to ameliorate the worst excesses of his murderous reign.