Soon after the military police came looking for the 25-year-old computer engineer at his family’s home, he fled Syria.

He bribed a security officer to briefly remove his name from the list of men wanted for mandatory military service and paid a taxi driver $1,000 to drive him across the border into Lebanon.

Like many young men living in government-controlled parts of Syria, he had been putting off conscription by paying $2,000 a year, hoping to avoid becoming cannon fodder for a military that has been hemorrhaging soldiers, either by death or defection, after more than four years of war.

The reluctance of young men like him to join has left the Syrian army even weaker as it fights a multifront war. Instead, it has pulled inward, focusing on protecting parts of the country that are essential to President Bashar al-Assad’s seat of power, say Middle East diplomats and a Syrian government official.

That weakness was most apparent during recent defeats in the northwest province of Idlib and the city of Palmyra; rebels and opposition groups said regime forces withdrew quickly rather than fight a prolonged battle.