Twenty-five years after the September 11th attacks, a top FBI official is warning that the inspiration behind those devastating assaults continues to fuel terrorism within the United States. Foreign terrorist organizations remain adaptable and agile, posing a persistent challenge to national security, according to FBI Co-Deputy Director Chris Raia.

Raia explained that while the FBI and the broader U.S. intelligence community are better equipped now to thwart large-scale, sophisticated plots akin to the 2001 al-Qaeda attacks, the nature of radicalization has shifted. The internet and social media have become potent tools for foreign terrorist groups to reach individuals within the U.S., leading to a rise in self-radicalized "lone offenders."

"We see people getting radicalized from the comforts of their own home, through social media, the internet," 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." He noted that the FBI has arrested at least 16 individuals in the U.S. homeland over the past year and a half for allegedly plotting or supporting attacks on behalf of groups like al-Qaeda and ISIS.

Despite advancements in counterterrorism efforts since 9/11, Raia emphasized that foreign terrorist organizations are actively seeking to exploit these new avenues of radicalization. The FBI is "way better postured now in 2026" due to legislative improvements and advancements within the bureau and the intelligence community, but the evolving threat landscape demands constant vigilance.

Raia stated that the 9/11 attacks remain a significant motivating factor for individuals radicalized online, referring to it as "their Super Bowl." He noted that "always, always references to 9/11" are found when examining the media and communications of individuals being investigated.

As an example, Raia cited the recent arrest of Jessica Bowie, 35, of Albany, New York, for allegedly plotting to bomb the state capitol. Charging documents revealed that Bowie posted on social media, "Praise be to Allah for September 11th," in the weeks leading up to her arrest. The head of the FBI's Albany field office, Craig Tremaroli, remarked that Bowie allegedly transitioned from a child waving an American flag after 9/11 to displaying stickers of the "fallen towers."

Overseas, the threat also persists, with reports indicating that ISIS and al-Qaeda continue to grow their ranks. A U.S. intelligence community report noted that ISIS has up to 18,000 members globally, while al-Qaeda's numbers reach up to 28,000 members. These groups, while potentially relying more on social media to connect with individuals in the U.S., maintain a significant global presence.

Raia's remarks underscore the ongoing challenges in counterterrorism, highlighting the shift from organized, externally directed plots to the more diffuse and harder-to-detect threat of online radicalization and lone offender attacks, with the legacy of 9/11 continuing to serve as a potent propaganda tool.