U.S.-backed Syrian forces advance into IS-held Raqqa

BEIRUT — U.S.-backed Syrian forces have advanced into opposite sides of Islamic State’s so-called Syrian capital of Raqqa, the forces and a war monitor said Saturday.

The Syrian Democratic Forces, a group of Kurdish and Arab militias supported by a U.S.-led coalition, began to attack Raqqa on Tuesday after a months-long campaign to cut it off.

The U.S.-led coalition estimates that Raqqa, which Islamic State seized from Syrian rebels in 2014 during their lightning advance in Syria and Iraq, is defended by 3,000-4,000 jihadists.

Also Saturday, Syrian activists said an airstrike in Raqqa killed at least seven civilians.

The activist collective Raqqa24 said seven people were killed Saturday when coalition aircraft bombed al-Nour street in Raqqa, in northern Syria.

The Britain-based Syrian Observatory for Human Rights said 13 civilians have been killed in coalition air raids over the past 24 hours.

The city has been a hub both for Islamic State’s military leaders and its bureaucrats, and has been used to plot attacks in countries around the world.

In another development, Russia said Saturday it had told the United States it was unacceptable for Washington to strike pro-government forces in Syria after the U.S. military carried out an airstrike on pro-Assad militia last month.

Russian Foreign Minister Sergey Lavrov relayed the message to U.S. Secretary of State Rex Tillerson in a phone call on Saturday initiated by the U.S. side, the Russian Foreign Ministry said in a statement.

Islamic State still has a long sweep of territory along Syria’s Euphrates valley and wide stretches of desert, despite recent losses to the SDF, the Syrian army and rebel groups.

To the west of Raqqa, the Syrian army and its allies have advanced into Islamic State territory and on Friday reached SDF lines near the town of Tabqa, 25 miles from the city.

The Syrian government has described the SDF’s war against Islamic State as “legitimate” and said its military priorities are further east, suggesting it does not plan to confront the group now.