James Foley

The reported killing of British militant Mohammed “Jihadi John” Emwazi is a significant blow to the Islamic State.

The Islamic State group released a graphic video Sunday in which a black-clad militant claims to have beheaded U.S. aid worker Peter Kassig, who was captured last year.

Islamic State extremists released a video purportedly showing the beheading of American journalist Steven Sotloff, and warning President Barack Obama that as long as U.S. airstrikes against the militant group continue, “our knife will continue to strike the necks of your people.”