A quarter-century after the September 11 attacks killed nearly 3,000 people in New York and Washington, security experts are sounding the alarm over what they describe as a dangerous erosion of the counter-terrorism infrastructure built in their wake. Budget cuts, the loss of experienced personnel, and a spreading sense of complacency, they warn, are recreating conditions similar to those that allowed al-Qaida to strike in the first place.

Bruce Hoffman, a terrorism expert at Georgetown University in Washington, told the US House permanent select committee on intelligence this year that "the counter-terrorism architecture built after 9/11 is eroding through budget cuts, personnel losses, and the diminution of terrorism as a national security priority." Colin Clarke of the Soufan Center, a security research organisation, described a "basket of factors" including fatigue after two decades of a global war on terror. "People were keen to pivot to something else," he said. Much of that pivot — towards long-term strategic competition with China and Russia — is broadly supported by analysts. But critics argue that decisions taken by the Trump administration have sharpened existing vulnerabilities, including what Clarke called a serious loss of morale inside the intelligence community.

Controversy has also surrounded a counter-terrorism strategy released by the administration in May, which analysts say prioritises political objectives over an accurate assessment of threats. Devorah Margolin of the Washington Institute for Near East Policy noted that while the strategy still acknowledged groups like Islamic State and al-Qaida, it downplayed the threat from rightwing extremism and expanded the use of counter-terrorism resources to cover cartels and gangs. "This has spread dwindling counter-terrorism resources even thinner," she said. Intelligence veterans have also criticised appointments to senior national intelligence posts as lacking sufficient top-level experience.

The broader legacy of the post-9/11 response itself remains deeply contested. Peter Neumann, a terrorism scholar at King's College London, has argued that the wars launched in response to the attacks amounted to a catastrophic strategic miscalculation born of panic and hysteria. The initial international solidarity that followed the attacks — and broad support for military action in Afghanistan — gave way to the invasion of Iraq, which Neumann calls "probably the ultimate moment of American hubris." That overreach, he argues, destabilised vast regions, fuelled ongoing terrorist movements including Islamic State, and allowed China to rise as a global power while Washington was consumed by unwinnable conflicts. Domestically, the war on terror's legacy includes disputed detention practices, mass surveillance laws, and abuse scandals that damaged the country's international standing.

Despite the absence of a mass-casualty attack on US soil since 2001, experts caution against complacency. Don Rassler of the Combating Terrorism Center at West Point warned that with fewer resources and fewer trained personnel, the US must now "accept more terrorist risk." The threat, analysts agree, has evolved — more fragmented, more ideologically diverse, and in some respects harder to track than the centralised al-Qaida of 2001. "There is a danger of believing the threat isn't there," Rassler said. "We have to be as clear-eyed as possible about it."