US 'reasonably certain' Jihadi John killed

The US military says it's "reasonably certain" it killed the ruthless Islamic State militant known as Jihadi John in a drone strike in Syria.

The masked British militant targeted in Thursday's strike sparked worldwide revulsion with his grisly executions of foreign aid workers and journalists in Syria on camera.

"We are reasonably certain that we killed the target that we intended to kill, which is Jihadi John," Colonel Steve Warren said from Baghdad in a briefing that was webcast live to reporters at the Pentagon on Friday.

Warren said it would take time for final formal confirmation that the high-value target killed in the Hellfire missile drone strike was indeed the 27-year-old Briton who was born Mohammed Emwazi in Kuwait.

But he stressed the US had "great confidence that this individual was Jihadi John".

"We know for a fact that the weapons system hit its intended target, and that the personnel who were on the receiving end of that weapons system were in fact killed," he said.

"This guy was a human animal, and killing him probably makes the world a little bit better place."

He added that Emwazi was "an ISIL celebrity" but not a crucial figure in the group's hierarchy.

"There is certainly a significant blow to their prestige of ISIL, but Jihadi John wasn't a major tactical figure or operational figure," Warren said.