In a letter to Rep. Eliot Engel, D-N.Y., General Martin Dempsey wrote that the US military could destroy Syria's air force, negating the Syrian government's ability to attack militants. But Dempsey warned that such a move "would also escalate and potentially further commit the United States to the conflict."

"Syria today is not about choosing between two sides but rather about choosing one among many sides," Dempsey wrote to Engel, whose office released the letter Wednesday. "It is my belief that the side we choose must be ready to promote their interests and ours when the balance shifts in their favor. Today, they are not."

The dour assessment from Dempsey comes as Syrian militant groups made fresh claims Wednesday that government forces carried out a "poisonous gas" attack near the capital Damascus.

Under the wrong pretext of using chemical weapons by Syrian government, which was not verified by UN agencies till now, White House officials said in June that the US would provide the terrorist groups with some direct military aid for the first time.

But thus far, the Obama administration has been reluctant to provide much more than humanitarian aid to the terrorist groups, which include some extremist elements with ties to al-Qaeda.

Eliot Engel, top Democrat on the House Foreign Affairs committee, proposed earlier that the US military make limited airstrikes against Syrian defense interests to help turn the tide in a civil war. The lawmaker expressed disappointment in Dempsey's comments.

"I remain deeply unsatisfied with our current strategy in Syria -- as we stand on the sidelines when the turmoil in that country continues to claim thousands of lives and sow instability throughout the region," said Engel. "I reject the notion that our involvement in Syria would simply constitute 'choosing sides' between one armed group and another."

NTJ/NJF