After several months of almost daily airstrikes on the emerging Islamic State faction in Afghanistan, U.S. commanders in Kabul are scaling back their threat assessment for the Iraq- and Syria-based extremist group that was gaining a foothold last year in one key Afghan province.

"The capacity of Daesh, we believe, has been lessened," Army Brig. Gen. Charles Cleveland, a top spokesman for U.S. forces in Afghanistan, said Thursday, using an alternative term for the Islamic State group, which is also known as ISIS or ISIL.

"We do think that they are being contained more than they probably were last fall," he said.

However, he added, "we do think that they still pose a real threat. And based on their past performance, they've got the ability to catch fire very quickly. So we do want to continue to have constant pressure on them."

Cleveland spoke to reporters at the Pentagon via teleconference from Kabul.

The emergence of an Islamic State faction in Afghanistan last year was a major concern for many U.S. officials. Although there was limited evidence of financial or operational support from the group's main hub in Iraq and Syria, the presence added a new and disturbing dimension to the 15-year-old war that has typically focused on the indigenous Taliban insurgency and the remnants of al-Qaida militant groups.

Intelligence officials believe there are few foreigners among the ISIS supporters in Afghanistan and most of them are local Afghans who broke away from the Taliban or other extremist groups.

Nevertheless, the appearance of the group's flag in Nangarhar province prompted the White House in January to expand the military's authorization for targeting Islamic State militants in Afghanistan. Last year, U.S. aircraft could strike ISIS militants only if they somehow threatened U.S. forces. But the Obama administration approved "status-based" authorities, meaning U.S. aircraft now can strike ISIS militants anytime anywhere simply because they are ISIS militants.

Since then, the U.S. and its allies launched between 70 and 80 airstrikes on Islamic State militants in Afghanistan, Cleveland said.

Most of those targets were individual militants in Nangarhar province near the Pakistani border, which has become a base of support for ISIS.

For months, U.S. military officials have estimated the size of the ISIS force in Afghanistan to range between 1,000 and 3,000. Cleveland noted Thursday that the current number is "probably the lower end" of that range.

"We think that we have significantly decreased the footprint that they have in Afghanistan. ... About three months or so ago, we thought that Daesh was probably in about six to eight districts. Today, we think they're probably in about two to three districts," Cleveland said.

The shrinking ISIS force is likely the result of some of those militants being killed in airstrikes, others laying down their arms and others defecting to the Taliban or other extremist groups in Afghanistan, he said.

Nevertheless, the general said, military officials remain concerned about the Islamic State threat and its potential to grow rapidly as it appeared to in Iraq and Syria in 2013 and 2014.

The shifting assessments about the ISIS threat in Afghanistan come at a time when top U.S. officials are reviewing President Obama's plans to cut the force of about 10,000 American troops in the country to 5,500 by the end of the year.

The new top commander in Kabul, Army Gen. John "Mick" Nicholson, who assumed command March 2, is drawing up a series of recommendations for the White House.

Cleveland said the ISIS presence in Nangarhar will be one of of many factors Nicholson considers when planning for the U.S. mission there.

"Daesh really does present the potential to be just an enormous threat. Obviously we have all seen them, how rapidly they've been able to spread in other parts of the world."