Which major event significantly shifted U.S. foreign policy after 2001?

The September 11 attacks in 2001 were a pivotal turning point for U.S. foreign policy, marking a significant shift toward a more aggressive stance against terrorism. Following the attacks, the U.S. government launched the War on Terror, which included military interventions in Afghanistan to dismantle the Taliban regime that was harboring al-Qaeda, the organization responsible for the attacks. This event led to a profound alteration in diplomatic relations, military strategy, and security policies, emphasizing counterterrorism efforts globally.

The impact of these attacks also extended to domestic policies, shaping national security legislation and practices, and altering how the U.S. engaged with both allies and adversaries. This was in stark contrast to previous foreign policy frameworks, which were predominantly influenced by the geopolitical struggles of the Cold War, regional conflicts like the Vietnam War, or specific military operations such as Operation Desert Storm. The focus on counterterrorism that emerged after 9/11 introduced a new era of American foreign policy characterized by the preemptive strikes and a heightened emphasis on national security.