What was the United States' first response to the terrorist attack of September 11 2001?

The United States' first response to the September 11, 2001 terrorist attacks was a declaration of a national emergency and an immediate mobilization of military and security forces. President George W. Bush addressed the nation, vowing to hold accountable those responsible for the attacks. Subsequently, the U.S. launched Operation Enduring Freedom, targeting the Taliban regime in Afghanistan that had provided sanctuary to al-Qaeda, the group responsible for the attacks. This marked the beginning of a protracted military campaign aimed at combating terrorism globally.