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…

“This army is going to start breaking,” said Jeffrey White, a former Defense Intelligence Agency analyst now studying Syria for the Washington Institute for Near East Policy. “Not the whole thing at once, but pieces of it will break.”