The Trump administration should now be discovering just what Russia’s word in Syria is worth.

Last year Russia brokered a series of cease-fires, or “deescalation zones,” in Syria, including one with the United States covering the southwest corner of the country. The Kremlin claimed its aim was to wind down the country’s civil war and lay the groundwork for a peace deal between the regime of Bashar Assad and rebel groups, some of them Western-backed.

Longtime observers of the Syrian war wondered if the cease-fires, like many previously agreed to by Russia and the Assad regime, would be broken as soon as the allies were prepared to launch new offensives against rebel-held areas. But President Donald Trump and his aides expressed optimism that Russian President Vladimir Putin was sincere. “If we get … a few more [cease-fires], all of a sudden we are going to have no bullets being fired in Syria,” Trump said in July. “I think there is a level of commitment on the part of the Russian government,” said Secretary of State Rex Tillerson.

The administration should now be discovering, as the Obama administration did before it, just what Russia’s word in Syria is worth. With heavy Russian air support, Syrian government forces have been conducting new offensives against two of the de-escalation zones, the Damascus suburb of Eastern Ghouta and the northern province of Idlib. As in the past, the tactics include war crimes, including the deliberate bombing of hospitals. In Idlib, where hundreds of thousands of Syrians took refuge during previous stages of the war, another mass exodus is underway, with more than 100,000 people fleeing north toward the Turkish border.

The onslaught in Idlib has drawn sharp protests from Turkey, with which Russia brokered the cease-fire in the area. Russia, in turn, has complained about attacks on one of its air bases using primitive drones of unknown origin. The Trump administration, meanwhile, is doing its best to ignore the new bloodshed. Officials are playing down the Idlib fighting on the grounds that the area is dominated by al-Qaedalinked rebel groups.

That explanation, which has been the standard excuse of the Assad regime and Russia for breaking previous commitments, is all too convenient. While extremist groups control a large part of Idlib, Turkey says moderate Free Syrian Army units are involved in the fighting — an assertion that we also heard from several FSA leaders now visiting Washington.

The mass of refugees being driven toward Turkey, with no protection from the winter weather, are not terrorists. And if the offensive is successful, the result will be the further entrenchment in Syria of not just Russia but also Iran, the Assad regime’s closest ally.

The United States, in short, stands to lose — again — to Russia in Syria. The Assad regime is relentlessly seeking to restore its control over the entire country by force, and Moscow is actively abetting it. By declining to challenge or even protest this brutal strategy, the Trump administration reveals its weakness. The members of The Denver Post’s editorial board are William Dean Singleton, chairman; Mac Tully, CEO and publisher; Chuck Plunkett, editor of the editorial pages; Megan Schrader, editorial writer; and Cohen Peart, opinion editor.