“There really has been no gain of territory, significant gain of territory since the departure of many of those fighters,” Colonel Dillon said.
The Kurdish-led Syrian Democratic Forces were the mainstay in routing the Islamic State from Raqqa and chasing insurgents fleeing south along the Euphrates River Valley to the Iraqi border. Without them, the remaining, less capable Syrian Arab militia have struggled to contain the few hundred fighters left in two main areas: Hajin, along the Euphrates River north of Abu Kamal; and Dashisha, east of Deir al-Zour, along the Syria-Iraq border.
“That is where ISIS in eastern Syria is concentrated and that’s where we are going after them,” Colonel Dillon said.
And it is an issue not only for the United States and other Western air forces. Using intelligence provided by the coalition, Iraqi fighter jets on April 19 attacked ISIS targets near Hajin, Syria, that Iraqi and American officials said threatened Iraqi security just across the border.
“Iraqi air forces strike #ISIS terrorists in eastern #Syria organizing to threaten western #Iraq,” Brett H. McGurk, the American presidential special envoy to the anti-ISIS coalition, said in a tweet. “More surprises in store in these few remaining ISIS havens.”
The strikes are the result of what the military calls deliberate targeting (as opposed to dynamic targeting in support of ground forces on the move attacking ISIS positions). With the insurgents hunkered down in the two pockets, dozens of American and allied spy planes have taken turns hovering over the targets, chronicling what planners call “pattern of life” movements.
Once planners have confirmed an enemy bunker or headquarters through this lengthy observation, they wait for opportunities to strike when certain the risk to civilians is low.
“The coalition’s ability to effectively target and destroy these remaining ISIS terrorists is due in large part to a constant overhead presence of various ISR platforms that continuously soak up intelligence on ISIS remnants,” said a summary of the March air campaign released by the military, referring to intelligence, surveillance and reconnaissance planes or drones.
“We have found opportunities and exploited ISIS weaknesses to conduct limited attacks,” Colonel Dillon said last week. “And now we’re starting to see some more strikes as a result of that.”
Still, allied airstrikes in Syria plummeted to 294 last month from 747 in February, and from 3,878 in March 2017. To some extent, that is to be expected as the number of potential ISIS targets dwindles. But the exodus of Syrian Kurdish fighters has also played into the decline.
The shifting tactics come at a time when ISIS has been able to reclaim some territory, particularly west of the Euphrates River, in area controlled by the Syrian army and its Russian military patrons.
ISIS is conducting more attacks on the western side of the Euphrates, outside of Abu Kamal, against forces aligned with the government of President Bashar al-Assad, American and other western analysts said. There are also reports of ISIS fighters seizing some neighborhoods in southern Damascus, the Syrian capital.
“The campaign against ISIS has not broken the organization’s will or capability to continue to fight,” said Jennifer Cafarella, a senior intelligence planner for the Institute for the Study of War, who added that she expects ISIS to increase its attacks across Iraq and Syria to mark this year’s Ramadan season, which begins May 15.
The Islamic State group launched a surprise attack near Mayadeen, a town in eastern Syria it had lost several months ago, killing at least 25 Syrian army forces, the Syrian Observatory for Human Rights monitor said.
Underscoring ISIS’s reach elsewhere in Syria, an American and a British soldier were killed by a roadside bomb in Manbij last month during an operation to go after a senior Islamic State leader there. Military officials are investigating the attack and say preliminary indications point to ISIS as the culprit.
Largely because of these small gains, Colonel Dillon said he and senior coalition commanders are now saying the coalition and its Syrian militia partners have reclaimed more than 90 percent of the territory the Islamic State captured in Iraq and Syria in 2014, instead of the 98 percent figure officials have been using for weeks.
Whether Syrian Kurdish forces will return to the east in large enough numbers to resume the offensive is unclear. “I know that’s something that we are urging and trying to get to,” Colonel Dillon said, “so that we can build up that combat power and start to push again in these areas and take ground.”