AYN ISSA, SYRIA (NYTIMES, AFP)- Forces backed by the United States have nearly sealed off the northern Syrian city of Raqqa, trying to trap as many as 2,500 hard-core Islamic State in Iraq and Syria (ISIS) militants defending the capital of their self-proclaimed caliphate.
The forces, known as the Syrian Democratic Forces, are made up of Syrian Kurdish and Arab fighters, and they have received crucial support from the US-led coalition fighting ISIS.
On Sunday, US-backed fighters also pierced the south for the first time, crossing the Euphrates River to enter a new part of the Syrian city, a monitor said. “Today, they entered Raqaa’s south for the first time and seized the Al-Hal market,” Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, said.
"And we shoot every boat we find," said Lt. Gen. Stephen J. Townsend, the US commander of the coalition force fighting the militants. "If you want to get out of Raqqa right now, you've got to build a poncho raft." As Iraqi forces are mopping up the last pockets of ISIS resistance in the Iraqi city of Mosul, the battle for Raqqa gives the US-led coalition - and the Trump administration - an opportunity to deliver a blow to ISIS by capturing its most visible territorial claim to a caliphate.
Still, the Kurdish and Arab fighters trained and equipped by the US-led coalition are just now carrying out the first push in what promises to be a bloody and difficult operation.
Most ISIS leaders and personnel responsible for administering the caliphate and plotting attacks have evacuated the city. They have relocated to Mayadin, a Syrian town east of Raqqa on the Euphrates River, according to coalition officials who are familiar with intelligence reports.
And ISIS militants are still defending strongholds in other towns in the Euphrates River valley, which stretches from Deir ez-Zor in Syria to Rawah in Iraq, as well as the Iraqi towns of Tal Afar and Huwaija.
For now, Raqqa is the focus, and Townsend met on Wednesday near Ayn Issa, Syria, with the commander of the Kurdish and Arab fighters to discuss the next phase of the fight.
Coalition officials said that the city was virtually surrounded, and that the one gap remaining along the river could be easily observed from the air. It is estimated that more than 1,100 militants have been killed in the past month. Of those who remain, almost a third are believed to be foreign fighters recruited by ISIS.
About 50,000 civilians also remain in the city, and military officials said the militants planned to use many as human shields.
US commanders and leaders of the Syrian Democratic Forces have sought to ensure that at least three-quarters of their roughly 6,000 fighters in and around Raqqa are Arab. The inclusion of the Syrian Kurds - generally regarded as the most battle-hardened fighters - in the offensive has outraged Turkey, a NATO ally whose relations with the United States have become increasingly fraught.
But Townsend acknowledged the importance of the Kurdish fighters in strengthening the Arab forces trying to rout ISIS from Raqqa.
"That's their role: to buttress, to help them do the hard stuff," he said.
The United States is providing much of the firepower in support of the Arab and Kurdish forces, using artillery, Himars satellite-guided rockets, Apache attack helicopters, armed drones and warplanes.
Fierce resistance is nonetheless expected by militants holed up in a cluster of tall buildings in northern Raqqa, redoubts that provide cover for Islamic State snipers and that will be hard for coalition-backed forces to clear.
"Mosul has got some big buildings, but they are spread out over the city," Townsend said of the city where Iraqi forces are battling ISIS militants. "Here there are a cluster of tall, dominant type of buildings. They are hard for any army on the planet."
One complication for the Raqqa operation, however, has been defused, at least for now. Recently escalating tensions between the United States and Russia over the scope of US and coalition airstrikes over Syria have seemingly eased.
After a US F/A-18 shot down a Syrian SU-22 that was dropping bombs near US-backed fighters two weeks ago, the Russian Defence Ministry warned that it might "target" any US and allied aircraft that flew west of the Euphrates.
Making the Euphrates a boundary for coalition air and ground operations would have interfered with the Raqqa campaign.
Even as Moscow was issuing dire warnings, however, Townsend was speaking with his Russian counterpart, Col. Gen. Sergei Surovikin, to reach an agreement for a way to separate the Syrian government's ground forces, and the Iranian militias that fight with them, from the fighters backed by the US-led coalition.
The line that the two commanders agreed upon runs in an arc from the southern shore of Lake Assad to a small town east of Raqqa. The line establishes a roughly 12-mile buffer between Raqqa, where the coalition airstrikes are crucial to the Syrian fighters battling ISIS, and the area where Syrian government forces and their Iranian allies are permitted to operate.
So far, the line has been respected, but that has not always been the case. Last month, Townsend thought a buffer had been established only to see Syrian government forces attack fighters supported by the US coalition in the hamlet of Ja-Din, south of Tabqa.
That led to a phone conversation with Surovikin in which the two commanders agreed on a slightly modified line. But no sooner was that discussion concluded than a Syrian SU-22 warplane appeared.
"My guess is that we had agreement on the phone," Townsend said of his conversation with Surovikin. "But decisions and actions take a while to stop. It's like a train." After dropping bombs north of the line, the SU-22 warplane was shot down and crashed south of the boundary. The pilot was seen parachuting from the plane, but the Americans do not know if he survived.