US Secretary of State John Kerry said on Friday 13 November that US officials were still assessing the strike that targeted Islamic State (IS) militant known as Jihadi John, but he said the operation showed the group's days were numbered. On Thursday (12 November) the United States carried out an air strike in Syria targeting the militant, a British citizen named Mohammed Emwazi, who participated in gruesome videos showing the killings of American and British hostages, officials said.

"We are still assessing the result of the strike, but the terrorists associated with Daesh [Islamic State] need to know this: your days are numbered and you will be defeated. There is no future, no path forward for Daesh which does not lead ultimately to its destruction. And increasingly, we are becoming more clear and coordinated in that strategy," Kerry told a news conference in Tunis.

One US official, speaking on condition of anonymity, said the strike likely killed Emwazi, though it was too soon to be certain. If his death is confirmed, it would be a key strike in the US-led campaign against the group and would come more than a year after US President Barack Obama promised justice after the deaths of American hostages.

Emwazi participated in videos showing the killings of US journalists James Foley and Steven Sotloff, US aid worker Peter Kassig, British aid workers David Haines and Alan Henning, Japanese journalist Kenji Goto, and other hostages. Kerry was due to leave for the Austrian capital later in the day for international talks to resolve the conflict in Syria.