Hundreds of fighters from Iran-backed Iraqi militias crossed into Syria overnight to help the government fight rebels who seized Aleppo last week, Syrian and Iraqi sources said on Monday, and Tehran pledged to aid the Damascus government.

Iranian-backed Iraqi militias have deployed in Syria to back the government’s counteroffensive against a surprise advance by insurgents who seized the largest city of Aleppo

Approximately 200 Iraqi militiamen crossed into Syria overnight through the strategic Bou Kamal border crossing, according to an opposition war monitor.