Islamic State terrorists posted another brutal video of an apparent beheading to threaten Iraqi Kurdish leaders for helping the U.S., Agence France-Presse reported on Friday.

The video, titled “A Message in Blood to the Leaders of the American-Kurdish Alliance,”shows a soldier kneeling in an orange jumpsuit before the sickening murder, AFP reported.

It shows a cruel masked killer standing behind the captured fighter before the murder. Two more jihadists hold guns next to him.

The disturbing footage come after a video surfaced on Thursday, showing ISIS executing nearly 250 soldiers in Syria.

Meanwhile, Britain raised the country’s terror threat level from substantial to severe Friday, meaning that a terrorist attack is considered highly likely.

Home Secretary Theresa Mays said the decision to raise the threat level was related to developments in Iraq and Syria, but that there was no information to suggest an attack was imminent. Some of the plots are likely to involve fighters who have traveled from Britain and Europe to take part in fighting in the Middle East.

“We face a real and serious threat in the U.K. from international terrorism,” she said. “I would urge the public to remain vigilant and to report any suspicious activity to the police.”

May says the decision by the Joint Terrorism Analysis Center is made on the basis of intelligence and is independent of government. “Severe” is the second-highest of five levels.

British police have appealed to the public to help identify aspiring terrorists after the killing of an American journalist focused attention on extremism in the U.K.