Will death of ISIS propagandist 'Jihadi John' be a blow to recruitment?

US defense officials have said they are almost certain they have killed the British militant known as Jihadi John in a drone strike. If confirmed, his death would 'strike at the heart of Islamic State,' according to British officials.

The United States military has said it’s "reasonably certain" it has killed “Jihadi John,” the masked, British, Islamic State (IS, also called ISIS) militant who was featured in violent propaganda videos murdering Western aid workers and journalists.

According to US Army Col. Steven Warren, a US drone strike targeted a vehicle in Syria believed to be transporting Mohammed Emwazi popularly known as "Jihadi John" Thursday night. 

The US military has not confirmed whether or not Mr. Emwazi had died in the airstrikes. In the past the Pentagon has claimed to have killed militants who turned out to be alive.

"We are assessing the results of tonight's operation and will provide additional information as and where appropriate," Pentagon Press Secretary Peter Cook told ABC News. 

Mr. Emwazi, a well educated, middle-class computer programmer born in Kuwait and raised in London, joined IS in 2013. He became well known after he appeared in videos showing the murders of US journalists Steven Sotloff and James Foley, and a number of other Western hostages.

British Prime Minister David Cameron spoke at a press conference early Friday and said it was "the right thing to do."

"We cannot yet be certain if the strike was successful. I've always said we would do whatever it takes to track him down, we've been working with the United States around the clock," Cameron said.

On Twitter, a Syrian activist group called Raqqa is Being Slaughtered Silently, said a missile hit Emwazi's car directly in front of an IS court in Raqqa.

Opinions differ over the Pentagon's method of killing key figures of Islamist terror groups in counterterrorism operations using drone strikes. Critics of the strategy say that the deaths have done little to stop the spread of islamist groups and their control of territories in Middle East and Africa.

As The Christian Science Monitor previously reported, a study on terrorism leadership vacuums shows that that decapitation strikes may result in more violence against civilians "Leadership deficits promote terrorism by empowering lower level members of the organization, who have stronger incentives to harm civilians," Max Abrahms, an assistant professor of political science at Northeastern University and co-author of the study, wrote in a blog post. 

When drone strikes are carried out on higher ranking individuals, it results in "the rise of lower leaders who are not as experienced as the former leaders” and who are more prone to errors in judgment, according to Daniel Byman for Foreign Affairs.

For Emwazi, the Islamic State's best-known propagandist, his death “would be a significant step in the anti-IS fight for the West given his part in recruiting efforts and the terror group's overall public image,” according to CNN.

"Since ISIS has used propaganda and its 'winner' image to lure new adherents, when its propaganda figure is killed that makes it look more like a loser, more like the tide may be turning against it," Richard Clarke, a former counter-terrorism advisor to the White House told ABC News.