U.S. strikes Syria forces, says they threaten allies

The United States on Tuesday struck pro-government forces in Syria with airstrikes for the second time in less than three weeks, declaring them a threat to anti-Islamic State coalition fighters and allied troops training at a camp in the south of the country.

The strikes came after complicated and messy discussions that reflected Syria's crowded battlefield and the wide array of forces fighting for a piece of the embattled country.

The day began when forces supporting Syrian President Bashar Assad were attacked by what the U.S.-led coalition believes were Syrian fighters not affiliated with the coalition. It was not immediately clear exactly who was part of the attacking force, said one U.S. official, but casualties resulted. The U.S. had been urging the pro-Assad forces to leave the area near the camp.

Then, after talks with Russian officials, the U.S. agreed to allow pro-Assad forces to repel the attack and remove their wounded, said the official, who wasn't authorized to speak publicly on the matter and demanded anonymity.

But soon afterward, more pro-Assad forces began entering the area with anti-aircraft weapons and bulldozers that the coalition said were not part of the agreement or needed to treat or remove the wounded. The coalition issued warnings through its "de-confliction" line with Russia, but the official said those were ignored.

The U.S. doesn't speak directly with Assad's government, which it accuses of various atrocities over more than six years of civil war. Instead, it addresses problems with Syria indirectly, usually through Russian officials. Russia is a military ally of Assad's government.

According to a coalition statement, at least 60 pro-Assad fighters were about 25 miles from the coalition training area at Tanf, which is inside a protected zone near Syria's southern border with Jordan. A number of the fighters have been in that area since a previous U.S. airstrike on pro-Assad forces on May 18.

A second U.S. official said airstrikes destroyed two artillery pieces and an anti-aircraft weapon and damaged a tank. It wasn't clear how many forces were killed, said the official, who also was not authorized to discuss details of the operation publicly and spoke on condition of anonymity.

Officials said some pro-Assad forces likely remain in the area. It wasn't clear how many are there or whether they might be preparing to leave.

U.S. officials haven't identified the forces exactly, but they have described them as being backed or directed by Iran. It's not clear whether they're Iranian soldiers, Hezbollah members, Syrian troops or part of another militia.

The day's first attack came as a U.S.-backed Syrian force began an offensive to capture the northern city of Raqqa, the Islamic State's self-declared capital, after months of clearing operations. A U.S. commander said the battle will be long and difficult, but success would deliver a decisive blow to the idea of the Islamic State extremist group as a physical caliphate.

By early afternoon, opposition activists said, U.S.-backed fighters were trying to break into the city from the east, triggering intense clashes.

Raqqa was among the first cities captured by the Islamic State, in January 2014, and has been the home of some of the group's most prominent leaders.

Talal Sillo, a spokesman for the Kurdish-led Syrian Democratic Forces, told reporters that operations have begun in coordination with the U.S.-led coalition.

"We declare today the beginning of the great battle to liberate the city of Raqqa, the alleged capital of terrorism and terrorists," Sillo said at a news conference held in northern Syria. "Morale is high, and military readiness to implement the military plan is complete, in coordination with the U.S.-led coalition."

Syrian Democratic Forces fighters began advancing toward Raqqa in November, capturing wide areas of northern Syria from the extremists. Last week, they reached the northern and eastern gates of the city after intense clashes under the cover of U.S.-led airstrikes.

Raqqa is currently cut off from the east, north and west, and opposition activists have reported intense shelling and airstrikes on the city since Monday night, which killed at least 12 people.

The Islamic State has been fortifying its positions in Raqqa for months, setting up barriers and hanging sheets of cloth over main streets to provide cover from warplanes. A belt of land mines and militant checkpoints circles the city.