Syria condemned on Friday U.S. airstrikes in Eastern Syria, describing them as a negative indication of the new U.S. administration policies. The airstrikes killed at least 17, Reuters reported, citing a medical source.

The "cowardly" attack is against international law, Syria's foreign ministry argued, warning it would lead to an escalation in the region.

U.S. President Joe Biden on Thursday directed the airstrikes against facilities belonging to what the Pentagon said were Iran-backed militia. 

"At President Biden's direction, U.S. military forces earlier this evening conducted airstrikes against infrastructure utilized by Iranian-backed militant groups in eastern Syria. These strikes were authorized in response to recent attacks against American and Coalition personnel in Iraq, and to ongoing threats to those personnel," Pentagon spokesman John Kirby said in a statement.

A source from the Syrian military told a correspondent of China Media Group that there were multiple airstrikes near the port of Abu Kamal, a town in eastern Syria on the border with Iraq, around midnight on Thursday.

A U.S. official, speaking on the condition of anonymity, said the decision to carry out these strikes was meant to send a signal that while the United States wanted to punish the militias, it did not want the situation to spiral into a bigger conflict.

China urges all relevant parties to respect Syria's sovereignty, independence, and territorial integrity, the Chinese Foreign Ministry's spokesperson Wang Wenbin said on Friday in the daily press conference. 

Wang also called on all sides to avoid adding new factors to the current situation. 

The Kremlin said on Friday it was closely monitoring the situation in Syria and that it was in constant contact with Syrian authorities. 

Kremlin spokesman Dmitry Peskov said at a press conference that he could not say whether the U.S. had notified Russia of its plans in advance, adding that operational contacts were made through the military. 

On February 15, rockets hit the U.S. military base at Erbil International Airport killing one non-American contractor and injuring a number of American contractors and a U.S. service member. Another salvo struck a base hosting U.S. forces north of Baghdad days later hurting at least one contractor.

Some Western and Iraqi officials say the attacks, often claimed by little-known groups, are being carried out by militants with links to Kata'ib Hezbollah as a way for Iranian allies to harass U.S. forces without being held accountable.

Earlier this week, the Kata'ib Hezbollah group, one of the main Iran-aligned Iraqi militia groups, denied any role in the rocket attacks.

Under former U.S. President Donald Trump, tensions escalated, culminating in the U.S. killing of Iranian military leader Qassem Soleimani and a retaliatory Iranian ballistic missile attack against U.S. forces in Iraq last year.

(With input from Reuters)