TERRORISMThe Legacy of the 9/11 Attacks: Terror Threats Have Multiplied Published 11 September 2025 Nearly twenty-five years after the worst terrorist attack in U.S. history, the country faces a much different landscape of threats and counterterrorism challenges. The U.S. military handily defeated al-Qaeda and Taliban forces and supported the battlefield victory over forces of the so-called Islamic State, but it has largely abandoned soft power efforts that could counter their enduring appeal.