With diplomatic efforts dead and the future of Syria playing out on the battlefield, many of the Syrian government’s most powerful weapons, including helicopter gunships, fighter jets and tanks, are looking less potent and in some cases like a liability for the military of President Bashar al-Assad.

Rebels have turned part of Mr. Assad’s formidable arsenal on his own troops. Anti-Assad fighters on Wednesday shelled a military airport in the contested city of Aleppo with captured weapons. On Tuesday, rebels used commandeered Syrian Army tanks in a skirmish with Mr. Assad’s troops.

Perhaps even more worrying to Mr. Assad, his military has come to rely more heavily on equipment designed for a major battle with a foreign enemy, namely Israel, rather than a protracted civil conflict with his own people. Close observers of his military say Syria is having trouble keeping its sophisticated and maintenance-intensive weapons functioning.

The strain is likely to grow more acute as the government depends on helicopter gunships to extend its reach to parts of the country rendered impassable to logistics convoys and even armored vehicles by the rebels’ improvised bombs.