Since the 2016 campaign, Donald Trump has threatened to withdraw from NAFTA. Can he? The question is complex. For one thing, NAFTA is not a treaty negotiated under the Treaty Clause of the Constitution, but rather a congressional–executive agreement, a creature of dubious constitutionality and ill-defined withdrawal and termination parameters. This Article reviews the scope of those restrictions and concludes that unilateral presidential withdrawal from NAFTA, although not without support, is ultimately unlawful. On one hand, unilateral presidential withdrawal would be valid as a matter of international law, and the NAFTA Implementation Act appears to be designed to terminate in the event of a lawful U.S. withdrawal from NAFTA. However, the President probably lacks statutory or constitutional authority to withdraw from NAFTA, and litigants might overcome political question hurdles by arguing that the NAFTA Implementation Act should not terminate where the President’s action exceeds the scope of his authority. Finally, because the Legislative Branch possesses constitutional authority over foreign commerce, Congress would also have several political remedies if it wishes to foreclose unilateral executive withdrawal from NAFTA or other congressional–executive agreements.