On 22 May 1947, President Harry Truman signed the formal “Agreements on Aid to Greece and Turkey,” the central pillars of what became known as the “Truman Doctrine.” Though the principles of the policy were first articulated in a speech to a joint session of Congress on 12 March 1947, it took two months for Truman to line up the funding for Greece and Turkey and get the legislation passed through Congress.

In his March address, Truman reminded his audience of the recent British announcement — a warning, really — that they could no longer provide the primary economic and military support to the Greek government in its fight against the Greek Communist Party, and could not prevent a spillover of the conflict into Turkey. Truman asserted that these developments represented a seismic shift in post-war international relations. The United States, he declared, had to step forward into a leadership role in Europe and around the world. Nations across the globe, as he put it, were confronted with an existential threat. They thus faced a fundamental choice about whether or not states “based upon the will of the majority” with government structures designed to provide “guarantees of individual liberty” would continue. If unsupported in the face of anti-democratic forces, a way of life “based upon the will of a minority [might be] forcibly imposed upon the majority”, a government orientation which he contended depended on “terror and oppression.”

Ultimately, the “foreign policy and the national security of this country,” Truman reasoned, were at stake in the global conflict over democratic governance and thus in the particular tenuous situations confronting Greece and Turkey.

The fates of the two states were intertwined. Both nations had received British aid,  he said. If Turkey and Greece faltered, or “fell” to communists, then the stability of the Middle East would be at risk; thus US assistance also was “necessary for the maintenance of [Turkey’s] national integrity.”

The President therefore made the ambitious proposal that was elemental to his “doctrine”: thereafter “it must be the policy of the United States to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures.” Truman requested $400 million in assistance for the two nations, in a move that many at the time — and most subsequent scholarship — depicted as marking a sort of de facto onset of the Cold War.

While transformative, the precise significance of Truman’s speech is a subject of debate. As historian John Lewis Gaddis has argued, “despite their differences, critics and defenders of the Truman Doctrine tend to agree on two points: that the President’s statement marked a turning point of fundamental importance in the history of American foreign policy; and that US involvement in the Vietnam War grew logically, even inevitably, out of a policy Truman thus initiated.”

However, Truman’s speech and authorization of funding on which the principles depended was neither a subtle nor a decisive shift toward the strategy of containment as many later politicians and scholars have surmised. As Martin Folly observes in a superb piece on Harry Truman in the Oxford Encyclopedia of American Military and Diplomatic History: “It is easy to see the Marshall Plan for European economic recovery as following directly from the Truman Doctrine.” Folly goes on to note that this association is wrong. There is little evidence to support a claim that Truman or his powerful then-Undersecretary of State Dean Acheson conceived of the Doctrine as a first step toward, for instance, the measured but firm anti-Soviet resolution showed in the US response to the Berlin Crisis (in the form of the Berlin airlift) nor was the doctrine directly linked to the Marshall Plan as it developed in the year to come. However, as Folly suggests, the Doctrine “reflect[s] Truman’s own approach to foreign affairs as it had evolved, which was that the United States needed to act positively and decisively to defend its interests, and that those interests extended well beyond the Western Hemisphere.”

The major ideological shift represented by the Truman Doctrine and the aid to Greece and Turkey its its simultaneous rejection of the long-standing injunction to “steer clear of foreign entanglements” and an embrace of a heightened expansion of a sphere of influence logic. For the first time in US history, the nation’s peacetime vital interests were extended far outside of the Western Hemisphere to include Europe and, indeed, much of the world. According to Truman, it is “the policy of the United States to support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures.”

This new logic of pro-active aid and intervention to support “vital interests” (always hotly contested, continually open to interpretation) worldwide undergirds the ways in which the United States continues to debate the nation’s internationalist as well as unilateralist options abroad in Ukraine, Libya, Syria, Afghanistan, Nigeria, and elsewhere.

Wherever one stands on debates over the “proper” US role in the world and contemporary geopolitical challenges, the antecedents are clear. After 1947 American national security—and foreign relations more broadly — were no longer premised on a limited view of protecting the political and physical security of US territory and citizens. Instead, the aid agreement signed on 22 May 1947 clinched a formalized US commitment to (selectively) assist, preserve, intervene, and/or reshape the political integrity, structures, and stability of non-communist nations around the world. The consequences of this aid agreement were profound for the early Cold War and for the shape of international relations in the world today.