WASHINGTON (TIP): The Pentagon said late Thursday that it had targeted Mohammed Emwazi, a member of the Islamic State often referred to as Jihadi John, in an airstrike near Raqqa, Syria.

Peter Cook, the Pentagon press secretary, said in a statement that the military was “assessing the results” of the strike to determine if Emwazi had been killed.

Emwazi, considered the most prominent British member of the militant group, was shown in videos in 2014 and 2015 killing several U.S. and other Western hostages. European governments, including those in Britain and France, are grappling with how to stem the tide of thousands of European citizens who are traveling to Iraq and Syria to fight alongside the Islamic State.

Emwazi, born in Kuwait and reared in London, has appeared as a black-masked figure in videos in which U.S. journalists James Foley and Steven J. Sotloff and U.S. aid worker Peter Kassig are beheaded. The militant traveled to Syria in 2012.

Emwazi, who is in his mid-20s, grew up in a trim housing estate in West London and graduated from the University of Westminster with a degree in computer programming.

In the mid-2000s, he was part of a loose network of young Muslims, some with friendships going back to childhood, who became deeply alienated from British and Western society.

The North London Boys, as the network is sometimes called, has sent dozens of young men to fight, first in Somalia and more recently in Syria.

The men appear to have been motivated initially by a civil war in Somalia.

Court documents show that Emwazi and others were well known to the British security services. According to a legal document from 2012, they were part of “a network of United Kingdom and East African-based Islamist extremists involved in the provision of funds and equipment to Somalia for terrorism-related purposes.”