The Syrian military is coordinating with its various international allies to launch sweeping counterattacks against the rebel militias that captured Aleppo last week in a surprise offensive. Iranian-backed militia from Iraq have entered the conflict to support the Syrian efforts to maintain President Bashar Assad’s regime.

Islamist rebel group Hayat Tahrir al-Sham launched a lightning assault against pro-Assad forces in Aleppo. Here’s who else is fighting in Syria’s civil war.

The Syrian civil war has been heating up in recent weeks with rebel groups making significant gains in the northern part of the country. The U.S. is trying to cooperate with Russia to keep American troops safe.

The sudden assault by Syrian rebels has rapidly redrawn the civil war’s front lines and threatened once again the authority of President Bashar al-Assad.