With the fall of Communism in the Soviet Union and Eastern Europe, Americans hoped for an era of peace. Ethnic, religious, and nationalist crises soon flared around the world, creating a new threat—global terrorism. On September 11, 2001, hijacked airplanes crashed into the World Trade Center towers and the Pentagon. A fourth hijacked plane crashed in Pennsylvania. The United States responded by declaring war on terrorism, prompting Congress to create the Department of Homeland Security. A year later, Congress met in New York City, commemorating those who died and asserting its determination to overcome this new peril.