Top FBI official warns 9/11 is still inspiring terrorists inside America 25 years later

Foreign terrorist groups are "adaptable" and "agile," an FBI officials says.

Twenty five years after al-Qaeda struck inside the U.S. homeland in shocking and tragic ways, federal authorities are warning that the threat from foreign terrorist organizations has hardly gone away, and in some ways is more challenging to stop now than it was two decades ago.

"We see people getting radicalized from the comforts of their own home, through social media, the internet," the FBI's co-deputy director, Chris Raia, told ABC News. "Those are the folks that keep me up at night because it's just so much harder for us to detect those."

According to Raia, the FBI is better positioned now to stop a large-scale, sophisticated plot like al-Qaeda's attack in 2001, which killed nearly 3,000 people.

"Way better postured now in 2026, based on legislation, based on how far we've come in the [FBI] bureau, based on how far we've come in the U.S. intelligence community," Raia said.

But he said foreign terrorist organizations have shown themselves to be "adaptable" and "agile," so al-Qaeda and other major terrorist groups like ISIS are now relentlessly seeking to develop what Raia called "lone offenders" inside the United States.

In the past year and a half, the FBI has arrested at least 16 people inside the U.S. homeland for allegedly plotting or supporting plots to kill Americans on behalf of al-Qaeda or ISIS, officials say.

In March, the U.S. intelligence community released a report on the state of worldwide threats and noted that, while ISIS and al-Qaeda may be largely relying on social media to reach America, their numbers are actually growing overseas, with ISIS now boasting up to 18,000 members worldwide and al-Qaeda's ranks reaching up to 28,000 members.

Raia said that 25 years later, 9/11 continues to be a motivating factor for people radicalized online.

"That is their Super Bowl," Raia said. "Every time you start digging into their media, digging into their communications, there's always, always references to 9/11."

Just three weeks ago, the FBI arrested 35-year-old Jessica Bowie of Albany, New York, for allegedly plotting to bomb the state capitol there. Charging documents said that in the weeks before her arrest, she wrote on social media: "Praise be to Allah for September 11th."

At a press conference after her arrest, the head of the FBI's field office in Albany, Craig Tremaroli, noted that Bowie allegedly "went from a little girl waving the American flag after 9/11 to now having stickers of the fallen towers."

"Let that sink in," he said.

Bowie has not yet entered a plea in her case.

In his interview with ABC News, Raia rejected criticism that the FBI has been distracted by immigration enforcement and other priorities of the Trump administration.

"Our footprint when it comes to the immigration policy or immigration is very minimal," he said.

Raia said that while the FBI always wants more resources, he can assure Americans that fighting terrorism is among the FBI's top priorities and that the FBI has the resources they need to do that.

Raia said it's an ongoing chess match with the FBI trying to predict what terrorists may come up with next.

"Drones has really been forefront of my priorities," he said. "You would be silly to think that that's not coming to the United States at some point, and we are trying to stay ahead of that."

Nevertheless, Raia said that to truly protect the U.S. homeland, the FBI needs help from the public.

"See something, say something," he said. "That campaign that started 20-something years ago, that is just as important today in 2026, if not more important than it was in 2001."

ABC News' Luke Barr contributed to this report.