On the morning of September 11, 2001, Stuart Gottlieb, then a Senate foreign policy adviser, was driving to Capitol Hill when he heard reports of a plane striking the World Trade Center. Initially dismissed as an accident, the second impact made clear this was a deliberate attack. “Nothing will ever be the same again,” he recalled thinking.
Twenty-five years later, the United States has avoided another attack of that magnitude, yet the legacy of 9/11 continues to shape global affairs. The assault, more devastating than Pearl Harbor, was executed by a shadowy non-state actor, al Qaeda. Since then, counterterrorism has dominated American foreign policy much as containing communism did during the Cold War, with similar cycles of success and failure.
The most profound effect of 9/11 was shattering the prevailing assumptions about global threats and America's role. Four major shifts from that era remain guideposts today, ensuring terrorism stays a manageable challenge.
The End of the ‘End of History’
The attack occurred at the height of the post-Cold War “unipolar moment,” when Western leaders touted the triumph of liberal democracy and free markets. Yet the 1990s were rife with civil wars, weapons proliferation, and escalating attacks on U.S. targets—culminating in 9/11. That a terrorist network posed the first major post-Soviet threat highlighted the cost of neglecting non-Western regions. Today, state-based challenges from China, Russia, and Iran have further complicated the landscape.
The Rise of Non-State Actors
For centuries, states have been the primary actors in international relations. 9/11 rattled that state-centric system. Al Qaeda and its offshoots, like Islamic State, operate as powerful non-state global actors, with franchises across Africa, the Middle East, and South Asia, even after losing their territorial bases. Having no government to negotiate with has fundamentally altered national security strategy. As of 2023, U.S. forces were conducting counterterrorism operations in at least 78 countries, reflecting this forward-deployed posture.
Terrorism as Warfare
Before 9/11, the U.S. treated terrorism largely as a criminal justice matter, appropriate for groups like the PLO or IRA that sought attention, not mass casualties. But the attacks signaled a shift toward terrorism as an act of war, aimed at inflicting maximum destruction. Both Republican and Democratic administrations have embraced wartime powers. President Obama, despite promising to reverse Bush-era policies, expanded drone strikes and surveillance, albeit with greater constitutional oversight.
The Battle of Ideas
The attacks also exposed the deep ideological roots of Islamist militancy, which cannot be defeated solely by military means. The 9/11 Commission recommended confronting this ideology directly. Yet Washington has leaned heavily on military and surveillance tools, often neglecting the softer power of economic development and winning hearts and minds in vulnerable regions. To succeed long-term, the U.S. must balance force with partnership in Muslim countries and the developing world.
As the nation marks this somber anniversary, Congress is weighing civil liberties reforms, while the transatlantic alliance remains vital. The lessons of 9/11 continue to inform debates over national security and global engagement, but the unified response of that era is unlikely to recur. The challenge now is to adapt those lessons to a multipolar world where threats are diffuse and alliances more complex.
