The gruesome video showing the beheading of journalist James Foley may actually be fuelling the popularity of ISIS, which is likely unconcerned that the "barbarity" of the video will galvanize American support for U.S. airstrikes in Iraq.

"They [Islamic State militants] believe these actions serve them," said Scott Stewart, vice-president of tactical analysis for the geopolitical intelligence firm Stratfor.

"For months, they’ve been beheading, amputating the hands of thieves, crucifying people in areas they control in Syria," said Stewart, a former special agent with the U.S. State Department who was involved in hundreds of terrorism investigations.

"Despite these barbaric displays … it's been successful. They've been able to grow and flourish, and they have been able to attract people to their cause despite this barbarity — perhaps because of it."

Foley, a 40-year-old American freelance journalist, was kidnapped in November 2012 and held in captivity until he was executed by ISIS militants this week. The group released a video that shows Foley’s killing, and said other American journalists would also die if the U.S. did not cease its airstrikes in Iraq.

At the end of the video, a militant shows a second man, identified as Steven Sotloff, another American journalist, and warns that he could be the next captive to be killed.

ISIS, the militant group fighting to establish an Islamist state, is the heir apparent of al-Qaeda in Iraq, which beheaded many of its victims, including American businessman Nicholas Berg in 2004.

'The fact that they are now able to capture these people and turn them into props and hostages for their snuff films means they can restart this whole process again because people will watch.' - Aki Peritz, ex-CIA counter-terrorism analyst

"Everybody’s talking about it [Foley's death] and that’s exactly what they want. They want to cut through the media," Aki Peritz, a former CIA counter-terrorism analyst who was responsible for watching the beheading and execution videos of al-Qaeda in Iraq, said from Washington. "A very explicitly gruesome, but very effective tactic to get into the press.

"People will be turned off, but there’s going to be a certain subset who are turned on by this sort of stuff," said Peritz, who is the coauthor of Find, Fix, Finish: Inside the Counterterrorism Campaigns that Killed bin Laden and Devastated Al Qaeda.

'People will watch'

Peritz said that after Berg's execution in 2004, videos of foreigners who had been kidnapped in Iraq being beheaded were regularly released, eventually diminishing their shock value. As well, Western foreigners in Iraq became sparse, making it difficult to capture them. But there are a number journalists and aid workers who are currently in Iraq and who are all potential targets.

"The fact that they are now able to capture these people and turn them into props and hostages for their snuff films means they can restart this whole process again because people will watch," Peritz said.

The ISIS video is purposefully and carefully orchestrated, down to the shaving of the captives' heads and placing the prisoners in an orange Guantanamo Bay-type outfit, Stewart said.

"That was meant to show or portray they are a state and not just some group, and they have their own prisoners that they are holding."

Because Americans don't pay ransoms for hostages, victims like Foley are used for political reasons and then executed when convenient, Stewart said.

"These guys have killed thousands of people over just the past month," he said. "We’ve seen them line up scores of men and execute them in shallow graves in Iraq. Since [Foley's] a westerner and since he's a journalist, it’s attracting a lot of attention which is what they’re seeking."

Although Americans have been cool to the idea of more U.S involvement in Iraq, the recent video could galvanize more support for the mission. On Wednesday, the U.S. launched a new barrage of airstrikes against ISIS extremists.

Meanwhile, the State Department refused to rule out future U.S. military operations in Syria, suggesting that the beheading video could potentially backfire.

Tendency to undercut themselves

"They [ISIS] have a tendency to undercut themselves because of [their] ideology," Stewart said.

"I believe these ISIS guys are true believers. I don't think they are actually non-rational but I think they see the world through a different rationality than most of us," Stewart said. "And they believe that basically they are undefeatable. They believe that Allah is favouring them, so they believe they can be this brazen and they don't have to adhere to the normal common sense rationality that [says] 'hey, don't make this many enemies.'"

However, Peritz said ISIS would welcome a bigger military response from the U.S.

"War makes these kinds of organizations stronger. If you can bring America in in a big way, they can quickly paint them as stooges of their Shia government in Baghdad," Peritz said. "Long term, they want to create another enemy out of us."

With files from The Associated Press