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A wave of airstrikes against ISIS was just “the beginning” of Jordan’s retaliation for the burning death of a fighter pilot, its military declared while promising to attack the Islamist militants “until they are destroyed.”

Up to 20 Jordanian F-16 fighter jets carried out airstrikes against ISIS in Syria on Thursday, then flew over the hometown of the pilot murdered by militants — a coordinated and public show of defiance in response to the horrific killing of Muath al-Kasasbeh.

ISIS on Tuesday released a video showing the pilot, who was captured over Syria in December, being burned alive in a cage.

Jordan’s military released a video late Thursday showing its fighter jets preparing for the airstrikes, with military personnel writing slogans on missiles in chalk including: “You are the enemy of [true] Muslims.”

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It also released a statement pledging to continue with “the killing of evil where it hides,” saying the airstrikes were carried out “in response to the criminal, cowardly act … that was carried out by a treacherous and tyrannical gang against the body of our pure martyr.”

“This is the beginning... you will know who the Jordanians are,” it said.

Jordanian planes were taking the lead in anti-ISIS airstrikes on Friday, according to Pentagon sources.

Meanwhile, the Jordanian government is investigating the possibility that al-Kasasbeh ejected after being shot down by his own wingman, sources told NBC News. U.S. officials referred all questions to the Jordanians, who said that they have no ability to inspect the wreckage since it is in ISIS territory.

Separately, Jordanian authorities released an imprisoned spiritual leader linked to al Qaeda, Sheik Abu Mohammad al-Maqdisi, security sources told NBC News and Reuters.

I've travelled to Amman, Jordan where young people are on the streets protesting against ISIS... https://t.co/v5m9jUYyxb — Keir Simmons (@KeirSimmons) February 6, 2015

There was no immediate announcement of the reason behind the move. However, his release triggered speculation that al-Maqdisi, who once backed ISIS but now supports the rival al-Nusra Front, might denounce al-Kasasbeh’s killing.

King Abdullah, who on Thursday visited and consoled the dead pilot’s family in a public show of defiance, later called for global unity in the fight against terrorism and for understanding between Muslims and Christians.

"This is a war the world cannot afford to lose,” he said in a speech released through his ambassador to the U.S. in Washington. “But to win it, all of us must be in it.”

He said that more than 1,000 years before the Geneva Conventions on human rights, "Muslim soldiers were ordered not to kill a child, a woman, or an old person, not to destroy a tree, not to harm a priest, not to destroy a church."

King Abullah added: "These are the same values of Islam we were taught in school as children: not to destroy or desecrate a place where God is worshipped. Jordan is a Muslim country, with a deeply rooted Christian community ... Consensus, tolerance, moderation, the rule of law: these have helped make Jordan an oasis of stability, and the same values will ensure our future."

NBC News' Andrea Mitchell, Jim Miklaszewski and Moufaq Khatib contributed to this report.