White House and Pentagon officials have said that Islamic State fighters have been "on the run" for some months now. But military commanders on the ground are seeing new pockets of movement in a handful of areas in Syria, which has led to an uptick in coalition airstrikes, an official said Tuesday.

Army Col. Ryan Dillon, spokesman for Operation Inherent Resolve, said that officials hope to get members of the U.S.-backed Syrian Democratic Forces to move back from the Afrin region and help push pockets of ISIS fighters away from towns along the Euphrates River Valley.

"We have seen ISIS elements coming back and attacking, with success, pro-regime forces," Dillon said during a televised briefing at the Pentagon.

To combat the movements, since January, there has been an uptick in strikes, Dillon said. These have been coupled with "obstacles" coalition forces have established in the area to "contain ISIS in these areas."

Dillon did not elaborate on what sort of deterrences have been placed in the region.

"Over this time it has also allowed us to do some serious, deliberate target planning," he said.

The fighters have concentrated in Syria's eastern areas surrounding the river, such as Hajin, north of Abu Kamal, and in limited areas near Deir Ezzor toward the river's eastern tributary, mainly in Dashisha, Dillon said.

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"That is where ISIS in eastern Syria is concentrated, and that's where we're going after them," he said.

Separately, there have been ISIS fighters spotted in neighborhoods south of Damascus, Dillon said. In the wake of Saturday's strikes against a Syrian chemical weapons lab outside of Damascus and two equipment facilities outside Homs, strikes against ISIS have not slowed, he said.

Dillon said the coalition has had a slowdown point in retaking various territories since a large amount of SDF fighters left for the Afrin region in January.

"There really has been no gain of ... significant territory since the departure of many of those fighters that have left to go towards Afrin," Dillon said.

As a result, the coalition has become more dependent on aircraft.

"Are we going to see more Syrian Democratic Forces come back and reconstitute combat power in these areas?" Dillon said. "It's something that we are urging and trying to get to to build up that combat power and start to push again in these areas and take ground."

In March, the U.S. announced a "pause" in ground operations against ISIS in the middle Euphrates River Valley (MERV) as SDF units moved to attempt to recapture the border town of Afrin. Afrin has been a point of contention between Turkey and Kurdish fighters.

The Kurds -- or fighters of the People's Protection Units (YPG), which is the dominant force in the SDF -- held the town until Turkey began an offensive earlier this year to rid the town of their presence. Turkey considers the YPG, allied with the PKK (Kurdish Workers Party), to be a terrorist organization.

The YPG played the leading role in retaking Manbij from ISIS, which set the stage for the major victory of the war against ISIS in Syria -- the taking of the so-called ISIS "caliphate" in Raqqa.

Dillon on Tuesday said that U.S. advisers, alongside partner forces, still remain on Syria's northern border in Manbij given that ISIS could see a weak point and reconcentrate in the area at a future time.

"Just because ISIS is not flying their black flag, doesn't mean they're not a threat," Dillon said.

--Richard Sisk contributed to this report.

-- Oriana Pawlyk can be reached at oriana.pawlyk@military.com. Follow her on Twitter at @oriana0214.