Encouraged by what they view as fatal setbacks to the Syrian regime, several thousand of an estimated 250,000 Syrian exiles in Jordan have left in recent weeks to join the rebellion in their homeland.

The exodus has emptied hundreds of the safe houses, apartments and refugee tents that housed Syrians in Mafraq and other northern Jordanian cities, according to Syrian activists and Jordanian officials. Jordanian security officials, who spoke on condition of anonymity, said as many as 8,000 Syrians have crossed the border back into Syria in the past 10 days alone.

According to Syrian activists in Syria and Jordan, the sudden returns are a response to a call for reinforcements issued in early December by the rebel military council, the main umbrella organization of army defectors locked in a bloody war of attrition against regime forces loyal to Syrian President Bashar Assad. Activists said the response has been greatest among refugees in Jordan, because pro-Assad militias in Lebanon have prevented similar returns from that country and many Syrians in Turkey were already involved in the fight.