However, in late 2006, the U.S. Department of Homeland Security (DHS) announced the final rule of the Western Hemisphere Travel Initiative (WHTI), which pertained to new identification requirements for U.S. citizens and international travelers entering the states. This rule, which marked the first phase of the initiative, was implemented on January 23, 2007, specifying six forms of identification acceptable for crossing the U.S. border (depending on mode):[38][39]