Following the horrific execution of Jordanian air force pilot Moath al-Kasasbeh by the Islamic State, the Jordanian government announced the execution of two terrorists with ties to IS.

Sajida al-Rishawi, an Iraqi female terrorist who failed to carry out a suicide attack in 2005 and a sister of a powerful aide to the former head of al-Qaeda in Iraq, Abu Musab al-Zarqawi, was hung at dawn along with Ziad Karbouli, another top aide to the deceased leader of AQ in Iraq.  Al-Qaeda in Iraq grew into the Islamic State when the Syrian civil war broke out.

According to the Jordanian military, al-Kasasbeh was actually executed on January 3.  But the Islamic State carried on with negotiations to release the pilot and Japanese journalist Kenji Goto, demanding the release of al-Rishawi in exchange for the hostages.  Jordan balked when IS refused to give proof of life, and both men have now met brutal ends.

Some analysts believe that the particularly barbaric manner of al-Kasasbeh's death might backfire on IS.

CNN:

Analysts have predicted the brutality of its latest video could come back to bite ISIS.

"I think there's likely to be a backlash, particularly in Jordan," said Paul Cruickshank, a CNN terrorism analyst. "I think it's sort of going to rally support for King Abdullah and his participation in the anti-ISIS coalition."

ISIS is known to be holding at least two Western hostages still: John Cantlie, a British journalist who has appeared in a number of ISIS-produced videos and an American woman who is a 26-year-old aid worker.

"The propaganda factor, I think, is going to completely backfire on them and the reason I say that is: When was the last time you had a mob in the street of one of these Muslim countries that was not screaming 'death to America,' but in fact screaming, 'get revenge on ISIS,' which essentially means, team up with America," said Tom Fuentes, a CNN law enforcement analyst. "I think it's a huge mistake on the part of ISIS."

ISIS has recorded the deaths of its captives before, then disseminated the brutal footage online as propaganda. What makes the Jordanian pilot's case different is that he hailed from a Middle Eastern nation taking part in the anti-ISIS military coalition.

The manner of execution also is different. In previous ISIS videos, captives were beheaded. A masked man with a London accent, dubbed "Jihadi John," has appeared in at least six videos, standing near hostages.

Sometimes, ISIS has threatened who it will kill next.

At the end of its latest video, ISIS shows names and addresses of who it claims are Jordanian pilots. A reward is offered, and a voice says they are "wanted dead."

"I think they're sending a clear message to the Arab members of the coalition, and certainly Sunni Muslims who may be engaged in the fight against ISIS, that this is the way they're going to be treated. They're going to be treated brutally, and in fact, maybe perhaps more brutally than other members of the coalition," said Juan Zarate, a former U.S. deputy national security adviser.

The Islamic State executions have been theatrical productions – very slick, and designed to elicit maximum horror.  Could it be that IS believed that the world had become inured to the horrific nature of the beheadings and decided to go for maximum shock value by burning their hostage alive?  Might we see even more cruel and barbaric means of execution in the future?  The ISIS terrorists may be animals.  But they have a sophisticated understanding of modern communication techinques and philosophy.  They know what makes us tick, and they play to our nightmares in order to make themselves feared.

The world has never seen their like: barbarity coupled with a modern understanding of propaganda and psychology.  It just doesn't get much deadlier than that.