Terrorist Expatriation Act - Amends the Immigration and Nationality Act to include among those voluntary acts for which a U.S. national (by birth or naturalization) will be subject to loss of U.S. nationality: (1) providing material support or resources to a foreign terrorist organization as designated by the Secretary of State; (2) engaging in, or purposefully and materially supporting, hostilities against the United States; or (3) engaging in, or purposefully and materially supporting, hostilities against any country or armed force that is directly engaged along with, or that is providing direct operational support to, the United States in hostilities engaged in by the United States.