A video released online shows a Jordanian pilot captured by the Islamic State extremist group in Syria last month being burned to death by his captors following a week-long hostage drama.
The footage was released on militant websites and bore the logo of the extremist group's al-Furqan media service. The 20-minute-long video featured the slick production and graphics used in previous videos released by the group.
Lt. Muath al-Kaseasbeh (26) fell into the hands of the militants in December when his Jordanian F-16 crashed near Raqqa, Syria, the de-facto capital of the group's self-styled caliphate.
He was the first pilot from the US-led coalition battling the group to be captured.
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.
Jordan later confirmed the death and vowed "punishment and revenge".
"The military forces announce that the hero pilot, Muath al-Kaseasbeh, has fallen as a martyr, and ask God to accept him with the martyrs," armed forced spokesman Mamdouh al-Ameri said in a statement read on Jordanian TV.
"While the military forces mourn the martyr, they emphasise his blood will not be shed in vain. Our punishment and revenge will be as huge as the loss of the Jordanians."
President Barack Obama said that the video was more evidence of the group's "viciousness and barbarity".
He said it would "redouble the vigilance and determination on the part of our global coalition to make sure they are degraded and ultimately defeated."
It indicated that "whatever ideology they are operating out of is bankrupt".
British Prime Minister David Cameron condemned the "sickening murder" and said the barbaric act would "only strengthen" the resolve of the international community to defeat the militants.
The latest video emerged three days after Japanese journalist Kenji Goto was beheaded by the militants. The fate of the two captives had been linked but a video of Goto's purported killing released on Saturday made no mention of the pilot.
An audio message last week, also purportedly from the Islamic State group, only said the pilot would be killed if an al-Qa'ida prisoner was not released on Thursday.
Following militant demands, Jordan's government had said it was willing to trade the prisoner, Sajida al-Rishawim, for the pilot, but that it wanted proof of life first.
Al-Rishawi faces death in Jordan for her role in triple 2005 hotel bombings that killed 60 people. A scroll on Jordan TV said that the pilot was killed on January 3, raising questions over whether any of the hostage negotiations were sincere.
The video included images of the pilot showing signs of having been beaten, including a black eye.
At the end of the video he is shown wearing an orange jumpsuit and standing in an outdoor cage. A masked militant lights a line of fuel leading to the cage.
The video also threatened other purported Jordanian pilots.
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.
Yesterday's was the first to show a captive being burned alive.