WHTI is the joint Department of State (DOS) and Department of Homeland Security (DHS) plan to implement a key 9/11 Commission recommendation and the statutory mandates of the Intelligence Reform and Terrorism Prevention Act of 2004 (IRTPA). IRTPA, in part, required the DHS and DOS to develop and implement a plan to require all travelers, U.S. citizens and foreign nationals alike, to present a passport or other acceptable document that denotes identity and citizenship when entering the United States.