Jordan’s King Abdullah on Tuesday described the Islamic State (ISIS) as a “cowardly” organization, and added that its killing of pilot Maaz al-Kassasbeh will only strengthen Jordanians.

“We have received with all sorrow, grief and anger, the news of the martyrdom of the brave pilot Maaz al-Kassasbeh, may Allah bless his soul, at the hand of the terrorist and cowardly Daesh organization, this criminal, stray gang that has nothing to do with our true religion,” the King said in a statement quoted by the Jordan Times and in which he used an Arabic acronym for ISIS.

“At this difficult time, it is the duty of all citizens to unify their ranks and show the true character of the Jordanian people when they face hardships and plights, which will only strengthen us and reinforce our unity,” added King Abdullah, who is currently on a visit to the United States which he said he would cut short.

Earlier Tuesday, ISIS released a video purportedly showing the burning alive of al-Kassasbeh.

Kassasbeh was captured on December 24 after his F-16 jet crashed while on a mission over northern Syria as part of the US-led coalition campaign against the jihadists.

The highly produced, 22-minute video shows footage of Kassasbeh sitting at a table discussing coalition operations against ISIS, with flags from the various Western and Arab countries in the alliance projected in the background.

In response to the brutal killing, Jordan said it would execute five terrorist prisoners in revenge.

Speaking to Sky News Arabic under condition of anonymity, a Jordanian security official claimed Sajida al-Rishawi – a failed female suicide-bomber whose release ISIS had demanded in a previous video in exchange for Japanese hostage Kenji Goto – would have her execution sentence expedited along with four other Islamist terrorists, in response to the horrific execution of pilot Maaz al-Kassasbeh.

The five convicted terrorists would be executed “within hours” the source claimed.