Activists, analysts say that internal conflicts are posing the biggest threat to ISIS

Reports from activists and residents in areas under Islamic State control suggest that rising tensions between fighters, an increase in guerrilla attacks, and difficulty recruiting new members is harming the militant group, with the biggest threat coming from within its own ranks.

Tensions are high between foreign and local fighters in Syria, one local resident told The Washington Post, because foreign fighters live in the cities, where airstrikes are less common due to the risk of civilian casualties, and Syrian fighters are in rural areas where strikes occur more frequently. Another resident said that recently, a group of foreign fighters and Syrian fighters had a shootout in the street, because the Syrians had been told by a Kuwaiti commander to head to the front lines in Iraq.

"The key challenge facing ISIS right now is more internal than external," Lina Khatib, director of the Carnegie Middle East Center in Beirut, told The Post. "We're seeing basically a failure of the central tenet of ISIS ideology, which is to unify people of different origins under the caliphate. This is not working on the ground. It is making them less effective in governing and less effective in military operations."