This article historicizes the contemporary relationship between the United States, its leading United Nations allies, and the two Koreas through the lens of the post-1953 history of the Korean Armistice Agreement, demonstrating that the US-UN allies were not only responsible for significant violations of the truce, but also that these violations escalated the ongoing conflict. The article explores how the United States and its allies in the United Nations understood the legacies of war associated with the Armistice, how they conducted their diplomacy in relation to the Armistice Agreement, and how their reactions to a series of post-1953 crises—the American introduction of atomic weapons to South Korea in the latter part of the 1950s; American and allied diplomacy surrounding North Korea’s seizure in early 1968 of the US spy ship, the USS Pueblo; and the Joint Security Area (JSA) War Crisis of August 1976—involved warfare strategies intertwined with violations of the Armistice Agreement. Far from creating peace or stability, the manner in which successive American and allied UNC governments have dealt with the Armistice has fueled and escalated the ongoing militarization of the Korean peninsula, of which the contemporary nuclear crisis is just one obvious by-product. The Korean Armistice, constantly violated by North Korea and the UNC, and still not adhered to by South Korea today, has not inhibited conflict in Korea or mediated tension. Indeed, US-UNC violations of the Armistice have been a major reason that the agreement has become part of the many obstacles to creating peace on the Korean peninsula.