Challenges to the liberal order

September 11 and the war on terror

The September 11, 2001 al-Qaeda attacks on the World Trade Center and the Pentagon killed nearly 3,000 people. The U.S. responded with the war in Afghanistan (which lasted 20 years, ending in 2021 with Taliban return to power), the Iraq War (2003-2011, justified by claims about Iraqi weapons of mass destruction that proved false), and a broad "war on terror" that reshaped American foreign and domestic policy. The Iraq War in particular weakened American credibility and damaged the post-Cold War international order.