On September 11, 2001, the United States was attacked by Al Qaeda when terrorists hijacked and flew commercial airliners full of innocent civilians into the World Trade Center and the Pentagon.  This event led to the United States' War on Terror.  Within months, one of the first Hamas front organizations in the United States, the Holy Land Foundation, was designated as an "Specially Designated Terrorist," its doors shuttered and its assets frozen.  However, leaders in the US-based Hamas infrastructure adapted quickly to the development and continued, undeterred in pursuing their mission.