And reports from Iraq's government suggest ISIS leader Abu Bakr al-Baghdadi may have been hit
in airstrikes over the weekend -- though it's not clear whether he was wounded, whose strikes he may have been hit by and in what part of the country he may have been struck.
But if al-Baghdadi is dead, what would happen to the radical Sunni militant group?
Don't expect ISIS to just crumble.
"It will morph, and new leaders will emerge," retired U.S. Maj. Gen. James "Spider" Marks said. "In fact, bear in mind that ISIS leadership originated from Saddam's military. These are very conventionally trained, very professional leaders."
Odds are al-Baghdadi or the Shura Council, which handles the group's religious and military affairs, has planned this scenario in advance.
likely has a clear line of succession," said Lauren Squires of the Institute for the Study of War. "This is a bureaucratic organization with a deep bench ... either Baghdadi has signed off on the line of succession himself or the Shura Council has agreed to a line of succession."
Top two deputies
Al-Baghdadi has a Cabinet of advisers as well as two top deputies -- Abu Muslim al-Turkmani, who oversees ISIS' mission in Iraq, and Abu Ali al-Anbari, who is in charge of operations in Syria, according to the Terrorism Research and Analysis Consortium.
Both men are veteran Iraqi military officials who served under Saddam Hussein.
"These people who had previously served in Saddam Hussein's army were extremely brutal because Saddam Hussein's regime was very brutal," said Peter Neumann of King's College. "But they also inherited the disciplines and the military skills that are now benefiting ISIS in its campaign against its enemies."
Analysts say al-Turkmani could make a strong case to become the leader of ISIS if al-Baghdadi is taken out.
"He would also have had to have a lot of outstanding qualities either in the political or the military field, and that certainly makes him a potential contender," Neumann said.
Beneath each deputy are 12 governors for both Iraq and Syria. Those governors handle financial, military, legal, media and intelligence councils, among others.
What's interesting about the bureaucratic hierarchy of ISIS is that it looks a lot like those of some Western countries whose values it rejects -- except there's no democracy involved and there's a council tasked with considering who to behead.
Then there's Syrian Abu Mohammed al-Adnani, the chief spokesman for ISIS who could also take over the group.
In September, al-Adnani called for ISIS supporters to launch lone-wolf attacks.
Analysts say some of al-Baghdadi's top deputies were imprisoned with the spokesman at Camp Bucca, a U.S.-run detention center in Iraq where al-Baghdadi was also held for at least four years.
"He was able to trust these individuals as sharing his ideology, sharing his hatred for the West.," Squires said.
The Shura Council's importance
If al-Baghdadi is still alive, there's one group of people who can take him out even without the use of airstrikes or violence.
The Shura Council is the religious monitor for ISIS. Not only does it make sure all the local councils and governors are sticking to ISIS' version of Islamic law, it has the ability to stand up to al-Baghdadi.
"The Shura Council has the right to tell Baghdadi to go if he's not adhering to ISIS' religious standards," said Jasmine Opperman of the Terrorism Research and Analysis Consortium. "It would most probably never happen, but the fact that it's possible indicates the council's prominence."
She said the recent beheadings of Western hostages James Foley, Steven Sotloff, and David Haines would have fallen under the Shura council's purview.
On top of that, Opperman said, the Shura Council also has the power to censure the leadership for running afoul of its interpretation of Sharia law.
But what happens if al-Baghdadi dies might just be hypothetical for now. While some Iraqi officials say the ISIS leader was wounded in an airstrike, U.S. officials say they can't confirm whether al-Baghdadi was hit at all.