U.S. escalates airstrikes against Syrian government

June 8 (UPI) -- The U.S.-led coalition to fight the Islamic State has struck pro-government forces in Syria for a third time in recent weeks.

The attack Tuesday against Iranian-backed Shiite militia fighters took place near the At-Tanf Garrison on Syria's southern border. The Shiite fighters back Syrian President Bashar al-Assad's forces, and the officials with the U.S.-led coalition said they needed to be taken out.

"Despite previous warnings, pro-regime forces entered the agreed upon deconfliction zone with a tank, artillery, anti-aircraft weapons, armed technical vehicles and more than 60 soldiers posing a threat to coalition and partner forces based at the At Tanf Garrison," a coalition statement said.

"The coalition does not seek to fight Syrian regime or pro-regime forces, but remains ready to defend themselves if pro-regime forces refuse to vacate the deconfliction zone," the statement added. "The coalition calls on all parties in southern Syria to focus their efforts on the defeat of [the Islamic State], which is our common enemy and the greatest threat to regional and worldwide peace and security."

CNN reported that the the militia fighters were just inside a 34-mile so-called deconfliction zone the United States had set up weeks earlier to protect U.S. forces in the area.

The United States has carried out several airstrikes against IS in Syria in recent months, but pro-government forces have been targeted in recent weeks.

On May 19, the U.S. military hit pro-government forces with an airstrike for coming too close to a base where U.S. and British troops are training rebels to fight IS, although the pro-government forces are also fighting IS, as well as Syrian rebels.

The Syrian government, which is backed by Russia, denounced that airstrike because it said the base was illegitimate since the government did not give the United States or Britain permission to set up a military post in the country.

The U.S.-led offensive against the Syrian government first escalated in April when President Donald Trump approved the launching of 59 Tomahawk cruise missiles against a Syrian government airfield suspected of being the origin of a chemical attack that killed nearly 100 civilians.