The slaughter of civilians in Aleppo last week may have shocked the conscience of the world, but no one should have been surprised. Syria’s Assad regime has always treated opponents savagely, and its assault on Aleppo, once the country’s largest city, has been coming for a long time.

When Secretary of State John F. Kerry and U.N. Ambassador Samantha Power pleaded with Assad to observe the niceties of civilized warfare, they knew their words would likely have little impact.

The U.S. inability to stave off the fall of Aleppo was the tragic but predictable product of a mismatch between Obama’s rhetoric and his commitments.

Soon after the uprising against Assad began in 2011, Obama declared the United States on the side of the rebels and announced that the dictator’s days were numbered.

The president never backed up those words with action, though, because he believed there was no compelling U.S. interest that justified direct intervention in the civil war. He insisted that there was no military solution and dispatched Kerry to seek cease-fires and peace talks.

Assad and his allies in Russia and Iran decided, to the contrary, that there was a military solution — and, so far, they are turning out to be right.

The winners are the Assad regime, the Iranian Revolutionary Guard and Lebanese Hezbollah who supplied many of the ground troops, and Russia, which provided air power and special operations forces.

The city was the last major stronghold of the moderate rebels whom the United States had been supporting. Their defeat sends many of their surviving fighters into territory controlled by the more radical Conquest Front, al-Qaida’s affiliate in Syria.

The battle in Aleppo also took Syrian troops away from the eastern front where they’ve been sporadically fighting Islamic State, allowing that group to reconquer Palmyra.

So the fall of Aleppo is not only a humanitarian disaster; it’s a setback for hard-nosed U.S. interests, too.

In Obama’s defense, it’s true that there were never easy, cost-free alternatives to his policy of restraint. But it’s not true, as he also argued, that the only alternative was a full-scale U.S. invasion.

Obama aides spent years proposing less-costly alternatives, only to be turned down.

In 2012, then-Secretary of State Hillary Clinton and Defense Secretary Leon Panetta proposed arming moderate rebels who were already receiving aid from other Arab countries, but Obama rejected the idea.

In 2013, after Assad used chemical weapons against civilians, Obama announced that he would retaliate with U.S. military force — but had second thoughts.

In 2014, after Assad began dropping crude barrel bombs into rebel-held neighborhoods, aides proposed supplying anti-aircraft weapons to the insurgents, but they were denied.

Instead, in a half-measure, the United States sent anti-tank missiles, which helped the rebels win a series of victories on the ground and brought the war to an apparent stalemate in 2015.

At that point, though, Russia’s Vladimir Putin intervened, surprising the White House by sending air force units to back up Assad’s troops.

Meanwhile, Kerry doggedly negotiated a series of cease-fire agreements, none of which took hold. Although the Russians played along, they never restrained the Syrian military or its Iranian and Lebanese allies on the ground. Officials acknowledge privately that Syria has been the greatest foreign policy failure of their eight years in office.

Trump has suggested he might try to end the Syrian war by allying with Russia and leaving Assad in place. His national security adviser, Michael T. Flynn, has said he also wants to reduce Iran’s influence.

“Good luck,” said Hof. “We’re still coming at this from the sidelines, without much leverage to get what we want. That’s been the problem all along.”

Doyle McManus is a columnist for the Los Angeles Times.