A U.S. pilot prepares for a mission in the cockpit of an F-16 Fighting Falcon at Bagram Air Field in Afghanistan in November 2015. U.S. military officials said Thursday, Feb. 11, 2016, that coalition airstrikes and operations are increasing against an estimated 1,000 to 3,000 Islamic State fighters in Afghanistan.

WASHINGTON — The United States is increasing airstrikes and operations against an estimated 1,000 to 3,000 Islamic State fighters in eastern Afghanistan to keep them from establishing a base of operations there.

Brig. Gen. Wilson Shoffner, a Kabul-based spokesman for Operation Resolute Support, said many of the new Islamic State fighters are militants from other terror groups who have "rebranded" themselves as part of the Islamic State group.

The Islamic State first announced its presence in Afghanistan in January 2015 and is viewed now as "operationally emergent," Shoffner said.

With the expanded rules of engagement approved by President Barack Obama in December, U.S. forces have launched raids and airstrikes to keep the Islamic State in Afghanistan from coalescing. Shoffner said most of the estimated 1,000-3,000 Islamic State fighters in Afghanistan are located in the southern part of Nangarhar province, which borders Pakistan.

"We are seeing [the Islamic State group] attempting to do low-level recruiting and propaganda in in various places [in Afghanistan,]" Shoffner said. "Almost all of those with the exception of Nangarhar province in the east are unsuccessful. So, very, very low level activity with the exception of the east. And in the east, in Nangahar province, we are seeing [the Islamic State] attempting to establish a base of operations there."

Afghan security forces are attacking the fighters in Nangarhar to keep the group from growing.

The United States has "significantly increased pressure and the number of strikes…conducted against [the Islamic State] in Nangarhar province in the last three weeks,” Shoffner said, though he would not elaborate on how many airstrikes were conducted.

Shoffner said the Islamic State's growth in Nangarhar province was "relatively contained."

"What we are not seeing is [the Islamic State] having the ability from either Iraq or Syria to orchestrate operations in Afghanistan. We're not seeing [the Islamic State] having the ability to conduct operations in Afghanistan in more than one place at a time," he said.

copp.tara@Stripes.com

Twitter:@TaraCopp

