Today, there are an unprecedented number of disputes at the World Trade Organization (WTO) involving national security. The dramatic rise in trade disputes involving national security has resuscitated debate over the degree of discretion afforded to WTO Members as to when and how to invoke Article XXI, the Security Exception, of the General Agreement on Tariffs and Trade (GATT), with binding effect. As this paper will argue, archival investigation into state practice for the construction of the security exception within the framework of the International Trade Organization (ITO) produces a story with a deep context that illuminates the plausible legal interpretive steps involved in invoking Article XXI GATT. Due to the overwhelming influence the United States had in designing and constructing the exception, U.S. practice offers a revealing lens by which to study the history of Article XXI. The U.S. was the main architect in the design and placement of the security exception within the ITO. To the extent that Article XXI GATT is meant to clarify the bounds between trade multilateralism and national security, this paper seeks to explore what the text means through an historical investigation into U.S. practice, and the multifaceted considerations that shaped what the U.S. intended to convey with the language, phrasing, and placement of the security exception in the original multilateral trade bargain.