Shamsud-Din Jabbar's New Year's massacre in New Orleans, carried out with a pickup truck flying an ISIS flag, could embolden the terrorist organization to radicalize more Americans, experts told Fox News Digital.

Jabbar's younger brother told The New York Times he and his Army veteran brother were raised Christian in Beaumont, Texas, before the now-deceased attacker converted to Islam as an adult.

"What he did does not represent Islam," the younger brother said. "This is more some type of radicalization, not religion."

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He added that Jabbar did not know what he wanted to do in life and began his military career "to get some sort of discipline."

While he was traveling from his home in Texas to Louisiana on Tuesday, Jabbar posted videos to his Facebook account pledging his allegiance to ISIS, law enforcement sources said.

Retired FBI agents Scott Duffey and Chris Swecker told Fox News Digital Wednesday's attack could embolden ISIS, other terrorist groups or individuals who have been radicalized.

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"This is a time where ISIS is under extreme stress, and their existence is being threatened in Syria and elsewhere. It would make sense for them to double down on their message to radicalize Americans to put them into action and activate any cells that they have in place," Swecker said.

Before his rampage in New Orleans, Jabbar posted several videos on Facebook declaring his support for ISIS, the FBI said at a news conference Thursday.

"In the first video, Jabbar explains he only planned to harm his family and friends but was concerned the news headlines would not focus on the 'war between the believers and the disbelievers,'" FBI Deputy Assistant Director Christopher Raia said. 

ISIS and other terrorist organizations often use social media to recruit new members, experts said.

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"ISIS and other foreign adversaries use all sorts of social media platforms to spread anti-American ideologies, rhetoric and propaganda," Duffey said. "It's free speech and designed to slowly convert young people to start questioning their American and religious ideals.

"It starts off (with) soft messaging to attract people into their thought process," he added. "Links are often provided that lead people to additional messages… sowing division and distrust of government in young impressionable minds.

"I think there is often an underlying mental issue in the reader that attracts them to the message, which over time leads to… more encrypted messages of violence.

"It’s a win for them if someone does something like what he did yesterday."

Most people are radicalized by online materials, said John Ryan, who served as chief of the Port Authority of New York and New Jersey Police Department.

"Him being an IT person, it would mean he probably knows how to access the dark web where a lot more material is available," Ryan said of Jabbar's background in information technology.

"In regards to whether it could trigger other people, sadly there are a lot of keyboard warriors who are being exposed to this and searching for something to connect to. Given the high level of mental health issues in the aftermath of COVID and the number of protests in support of Hamas and pro-Palestine and anti-Israel, the answer is yes. Mostly lone wolf type of people."

Although law enforcement officers were initially searching for accomplices in the attack, the FBI said Thursday it appears Jabbar acted alone. However, Swecker said, that does not discount the possibility of an active terror cell within the country. 

"If his radicalization was as a result of the propaganda and calls to action from ISIS on the internet, this is [still] international terrorism. We’re calling him homegrown, but it’s directed from a terrorist organization," Swecker said. 

"Even if he doesn’t carry a card, even if he isn’t on the phone with the ISIS director but he’s being called to action by propaganda on their websites, it’s still international terrorism," he said. "That’s very much a part of the playbook for al Qaeda and these international groups."

Jabbar was stationed at Fort Bragg, now called Fort Liberty, in North Carolina, as was active-duty U.S. Army soldier Matthew Livelsberger, who police said intentionally set and died in an explosion that injured seven outside Trump International Hotel Las Vegas on Wednesday.

Investigators have uncovered no evidence of a connection between the Bourbon Street terror attack in New Orleans and the Cybertruck explosion in Las Vegas despite the suspects' shared military history.

"If they served at the same base, I think I’m still very open and there’s a distinct possibility that they linked up on the internet or with their prior military associations," Swecker said. "If [Livelsberger] was a convert, he would have been going to the same [religious] services as [Jabbar].

"What [Jabbar] did and what happened in Las Vegas does give credibility to the movement and creates that excitement in others who may be thinking about it [carrying] on their plan in a short time frame," Duffey said.