#2 Dwight Eisenhower: The Runner-Up
Everybody likes Ike it seems (well except of course the Guatemalans, the Iranians, and the Indonesians, and for good reason). His presidency gets high marks from historians and foreign policy analysts alike - and deservedly so.He played nuclear poker beautifully to end the Korean War and also convinced the Chinese from keeping their hands off Taiwan. His policy of ratcheting up the nuclear arms race lessened the chances of US-Soviet conflict and also prevented the military budget from spiraling out of control. His remainder method for defense spending (after domestic priorities the remainder would go to the Pentagon) brought some sanity to what he later dubbed the military-industrial complex.
Ike also gets points for his handling of the Suez crisis and staring down those in his own administration who wanted to support the French militarily when they were getting their clocks cleaned in Indochina. And he used Cold War fears to push for national highway system and more money for higher education, two smart national security investments. From the a political standpoint he quietly helped usher in the downfall of Joseph McCarthy; and more prominently his 1952 campaign had the intended effect of burying the isolationist wing of the GOP and enshrining an internationalist vision in US foreign policy. He was also a non-partisan on foreign policy issues; a far cry from Truman or the presidents who would follow in his footsteps.
As Sean Kay, a professor at Ohio Wesleyan University (and Eisenhower devotee) said to me; "what really made him a great President on foreign policy was his capacity to see American power in more than military terms, and to see the essential relationship between domestic programs, like education, and national security. I could not think of a more appropriate worldview today." It's hard to disagree.
#1 The Gold Standard: Franklin Roosevelt
On the strength alone of winning World War II and handling the delicate diplomacy of dealing with wartime US Allies, like Churchill, Stalin, de Gaulle and Chiang Kai-Shek Roosevelt is far away the greatest foreign policy president of the 20th century. With this record of accomplishment it's hardly even a contest.
When one considers also that he laid the groundwork for the international system, via the United Nations and the Bretton Woods institutions, he practically floats into the stratosphere. This latter accomplishment is among FDR's most enduring in that it re-shaped the global system after World War II. But even Roosevelt's lesser well-known achievements stand out. The Good Neighbor policy ended (at least temporarily) US military interventions into Latin America and solidified the support of Western Hemispheric leaders for America's larger foreign policy goals.
Critics will rightfully complain that Roosevelt stumbled into conflict with Japan (or manufactured the war in order to ensure a US entry intro to the larger European conflict); or that he sold out the Eastern Europe countries at Yalta. All fair charges, but then they are also reflective of the hard-nosed pragmatism that bookended Roosevelt's idealism. Obviously no president is perfect and even the best ones have their downsides. Indeed, few American presidents fall easily into the great or even really good category - in the 20th century Roosevelt is clearly the one who does.