Russia and the United States clashed at the United Nations on Tuesday, accusing each other of supporting terrorism during a Security Council meeting convened over a sudden escalation of fighting in Syria.

Air strikes also targeted Iran-backed militia groups supporting Syrian government forces in the strategically vital region, a security source in eastern Syria and a Syrian army so

Western powers including the United States and the European Union called for de-escalation in Syria on Monday following a surprise Islamist-led offensive last week, while allies of Syrian President Bashar al-Assad,

Syrian government forces and their Russian allies are battling to hold back the offensive, with Russia launching airstrikes on Aleppo and the western city of Idlib on Sunday as Syrian government forces regroup, according to monitoring group The Syrian Observatory for Human Rights.

In just a few days, a patchwork of rebel forces has seized control of a broad stretch of land in the west and northwest of Syria. But it’s unclear just how much support Syria’s weakened allies can provide.