As international inspectors make unexpected progress in securing Syria’s chemical weapon facilities, its chief arms supplier continues to prop up its conventional forces, according to two senior lawmakers.

In an interview with The Daily Beast, Rep. Mike Rogers, the Republican chairman of the House Permanent Select Committee on Intelligence, said Russia was continuing to sell spare parts and other components for Syria's anti-tank and air defense systems—as well as attack helicopters. "The Russians have not disrupted their resupply of the Syrians," Rogers said. "This includes very sophisticated systems that could be just as dangerous as the chemical weapons."

That assessment is supported by Rep. Eliot Engel, the ranking Democrat on the House Committee on Foreign Affairs. Speaking to reporters Tuesday, he said he supported the deal brokered by Russia to help disarm Syria’s chemical weapons, but he also acknowledged Moscow “will continue to sell Assad conventional weapons to keep him propped up for now."

The situation creates a dilemma for the Obama administration. For nearly two years, the White House has said Syrian President Bashar al-Assad must leave power. But after threatening air strikes in late August and early September, President Obama instead pursued a Russian offer to get Syria to declare and then give up its vast chemical weapons stockpile and production facilities.

That process has so far been successful. The Organization for the Prohibition of Chemical Weapons (OPCW), the U.N.-affiliated group that has conducted inspections so far in 17 Syrian chemical weapons facilities—efforts that contributed to its Nobel Peace Prize win this year—said the Syrian government has “cooperated fully” with inspectors.

But the OPCW and the U.N. have no mandate to stop Russia from continuing to supply Syria with advanced conventional weapons. Rogers said Russia’s continued shipments to Syria have included spare parts and equipment for attack helicopters as well as artillery and other kinds of air defense and anti-tank rockets. The U.S. Congressional Research Service estimated that between 2008 and 2011, Russia made conventional arms transfers to Syria worth $1.7 billion. More recently, Human Rights Watch has assessed that Russian-made thermobaric bombs were used in a government assault on the Syrian city of Raqqa at the end of September. Other Russian weapons Syria has used in the conflict include the T-72 tank, the Grad rocket, and the M240 mortar, according to Human Rights Watch.

Rogers said Russia’s decision to help get rid of Syria’s chemical weapons while continuing to arm the Assad regime with conventional weapons was a shrewd way to advance the regime’s interests. He noted, for example, that the White House has largely stopped calling for Assad to leave power, a key objective for Russia’s foreign policy in the region.

Rogers himself said he supported the administration’s policy to try to usher Assad out of power. But he also said the fall of the Syrian regime today would likely result in a scramble by rebels and terrorist groups for Syria’s arsenal.