DAMASCUS, Feb. 3 (Xinhua) -- Syria on Saturday denounced recent U.S. airstrikes on pro-Iran militias in the country, saying it aims to weaken Syria's fight against terrorism.

The U.S. aggression lacked any justification beyond an attempt to weaken the Syrian army and its allies in their fight against terrorism, said the Defense Ministry in a statement.

The targeted area is where the Syrian army is actively combating remnants of the Islamic State (IS) terrorist organization, it said, charging that the attack highlights the U.S. involvement and collaboration with the terror group.

The U.S. assault resulted in the loss of civilian and military lives, along with injuries and extensive damage to both public and private properties, it added.

The Syrian military affirmed its unwavering determination to defend Syria's land and people, vowing to continue its mission to eradicate terrorism and liberate the entire Syrian territory from any form of occupation.

The Britain-based Syrian Observatory for Human Rights, a war monitor, reported that 18 militants were killed as the strikes hit strongholds of the Iranian-backed militias in the eastern Syrian province of Deir al-Zour.