Why is Sept 11 2001 such an important date?

September 11, 2001, is a pivotal date in history due to the coordinated terrorist attacks carried out by al-Qaeda against the United States, which resulted in the deaths of nearly 3,000 people. The attacks on the World Trade Center in New York City and the Pentagon in Washington, D.C., profoundly impacted U.S. domestic and foreign policy, leading to the War on Terror, the invasion of Afghanistan, and significant changes in national security measures. The events of that day also fostered a lasting global sense of vulnerability and heightened tensions in international relations.