The Islamic State group released a video on social media on Tuesday showing a captive Jordanian pilot being burned alive. The 20-minute-long film was released on militant websites and bore the logo of the extremist group's al-Furqan media service.
The Jordanian government confirmed the death of Muath al-Kasaesbeh and said this had happened on January 3rd.
The video shows al-Kasaesbeh, who was seized after his F-16 jet crash-landed near the Syrian city of Raqqa in December, dressed in an orange jumpsuit stood inside a metal cage.
Armed militants surround the area. The cage and the pilot have been doused with fuel. One of the militants lights the cage from a distance. Al-Kasaesbeh is shown holding his head and screaming as the flames engulf him. The video also threatened other Jordanian pilots.
Though the authenticity of the footage could not be confirmed, the film featured the slick production and graphics used in previous videos released by the group.
On Tuesday afternoon, President Barack Obama said that if a video showing the immolation of the pilot is authentic, it would be more evidence of the group's "viciousness and barbarity" and that it would "redouble the vigilance and determination on the part of our global coalition to make sure they are degraded and ultimately defeated".
The "sickening murder" of Jordanian pilot Lt Muath al-Kasaesbeh by Islamic State will only "strengthen resolve" to defeat them, Prime Minister David Cameron said.
Former Liberal Democrat leader Sir Menzies Campbell said: "These events simply underline that there is no level of barbarity to which IS is not willing to sink in support of its cause. The administration in Jordan will find itself in an extraordinarily difficult position as a result of this murder.
"But the lesson is surely that where IS triumphs it will allow no quarter to those who are opposed or unsympathetic to its views. Their hard line has to be met by a hard line on the part of the coalition."
Following al-Kasaesbeh capture IS militants initiated a Twitter discussion on the best method to kill the pilot using the Arabic hashtag “Suggest a Way to Kill the Jordanian Pilot Pig”. The tweets, which were sent from IS-affiliated accounts, were retweeted thousands of times.
Twitter responses included, "beheading", "burning him alive" and "running him over with a bulldozer".
The 26-year-old Jordanian was the first foreign military pilot to fall into the extremists' hands since an international coalition began its aerial campaign against IS in September.
At a tribal meeting place where the pilot's relatives have waited for weeks for word on his fate, chants against Jordan's King Abdullah II erupted and some family members wept. An uncle shouted in Arabic: "I received a phone call from the chief of staff saying God bless his soul." The pilot's father, Safi, was surrounded by family members.
The terrorist group has repeatedly threatened to execute al-Kasaesbeh, most recently in a video released last week. There was hope of the Jordanian's release in exchange for a female suicide bomber Sajida al-Rishawi, who has been held on death row since 2006. Al-Rishawi faces death in Jordan for her role in triple 2005 hotel bombings that killed 60 people.
The Jordanian government said an exchange was possible, however not without proof that their pilot was alive.
On Saturday, the Islamic State released a video showing the beheading of Japanese journalist Kenji Goto.
The Islamic State extremist group, which controls around a third of Syria and neighboring Iraq, has issued a series of grisly videos showing the killing of captives, including two American journalists, an American aid worker and two British aid workers. Tuesday's was the first to show a captive being burned alive.