The U.S. government is considering a military response to the new ISIS video featuring a murdered American aid worker. In the meantime, Middle East analysts are divided over whether details in the video signal a change in the jihadi group's strategy.

Released online on Sunday, the latest video shows the severed head of 26-year-old Peter Kassig, a former U.S. Army Ranger turned aid worker in Syria, as well as the decapitation of a group of Syrian soldiers.

What is striking to some observers is that, unlike previous beheading videos, only one of the killers from the Islamic State of Iraq and Syria (ISIS) is wearing a hood in this video. Every other member's face is completely visible – families in Wales and France have even come forward saying their sons are among the ISIS killers.

Loch Johnson, an international affairs professor at the University of Georgia, says unmasking the perpetrators is a way for ISIS to amplify the shock value, making it more "personal" and "more wrenching for people in the West to see."

But Firas Abi Ali, a London-based senior analyst at the global intelligence group IHS, believes the lack of facial covering is not so much a change in strategy as a way for ISIS to "show a little more confidence."

Says Ali, "It's just a way of saying, 'We're not afraid.'"

The clip is the latest in a series of beheading videos produced by ISIS, which has previously killed U.S. journalists James Foley and Steven Sotloff and British aid workers David Haines and Alan Henning on camera.

Act of provocation

While it is impossible to discern the ultimate aim of these videos, many observers believe they are an act of provocation to get the U.S. and other Western nations involved in Iraq, and thereby recruit more anti-Western jihadis, says Roland Paris, research chair in international security at the University of Ottawa.

The video shows the severed head of U.S. aid worker and former Army Ranger Peter Kassig. (Kassig Family/Associated Press)

The videos produced by the militant Sunni group also have the effect of intimidating Shia and moderate Sunnis who may oppose ISIS's attempt to establish a caliphate, or Islamic state, that straddles Iraq and Syria, says Paris.

The only consistent figure in all of these videos — and the only one wearing a mask in the latest clip — is the black-clad, British-accented man speaking to the camera.

Known in the Western media as "Jihadi John," he effectively narrates and rationalizes the acts, and as such has become the subject of worldwide scrutiny.

Standing by the severed head of Peter Kassig in the latest video, Jihadi John says, "Here we are burying the first American crusader" in Dabiq, a town in northwestern Syria, near the Turkish border.

Then, addressing the Western forces currently conducting airstrikes against ISIS, he says, "Eagerly waiting for the remainder of your armies to arrive."

Given that ISIS is willing to show the faces of other fighters on camera, IHS's Ali believes that keeping Jihadi John concealed isn't so much about protecting his identity as recognizing that the masked man has "become a brand, in a way."

Different quality videos

Another way that the latest clip differs from previous ISIS videos is that it does not actually depict Kassig's beheading.

While the execution of the Syrian soldiers is captured in high-definition video with multiple camera angles, slow-motion passages and Hollywood-style sound effects, the segment featuring Kassig seems to have been shot after the fact, and is noticeably amateurish-looking.

Some believe the two segments were shot at different times.

A man believed to be Nasser Muthana has appeared in an ISIS recruiting video, and his father in Cardiff, Wales, says he believes Muthana can also be seen in the most recent ISIS beheading video. (YouTube)

"It's hard to tell why this video is different from the previous ones," says Paris.

One possibility, says Paris, is that because of the U.S.-led airstrikes against them, ISIS members are under greater pressure and "don't have the same means and time and latitude to produce high-quality video like they did in the past."

There is also a theory that Kassig put up a fight and wouldn't cooperate.

Ali says that one of the most puzzling details surrounding Kassig's death are reports that he converted to Islam while in captivity and took the name Abdul-Rahman.

"I honestly don't know if this is true," Ali says.

Ali pointed out that a number of Arabic media outlets have been reporting that Kassig actually converted to Islam prior to his abduction by ISIS in 2013, which may be "an attempt by the Arabic media to discredit ISIS and say, 'Look, they're killing a convert.'"

Given that ISIS claims to uphold Islamic law, the group is undoubtedly cognizant of depicting acts on camera that would upset potential recruits, says the University of Georgia's Johnson.

He says that while Peter Kassig's death has shocked the world, many people are also concerned about the fate of a female U.S. aid worker currently being held by ISIS. Her identity is unknown, as U.S. officials and the woman's family have requested her name not be made public.

Executing a Western woman on camera "would be like throwing a can of kerosene on the fire," says Johnson.

"I think it would really ratchet up the whole determination of the Western nations to defeat this barbarous group."