From: "Emmanuel Gustin"

Another big difference is that FDR made a big effort to build
alliances,

FDR also called Europe an incubator of wars, and it was one of his major
postwar policy goals to see that Europe was permanently disarmed.
Roosevelt’s vision was of a Europe that had been rendered strategically
irrelevant. As historian John Lamberton Harper has put it, he wanted “to
bring about a radical reduction in the weight of Europe” and thereby make
possible “the retirement of Europe from world politics.” This would enable
the US to go back to being left alone to pursue its own destiny in peace.
Of course, he died too soon to see his vision to full fruition. Truman turned
away from Roosevelt's vision, listening to George Kennan, who wanted to restore
Europe (really mostly Britain) to something like its pre-WWOne role in the
world with the US going back to its of the same. But Truman ultimately relied
on Dean Acheson's interventionist policies, which could be described as
Roosevelt's with teeth. These established the United States as a permanent
power in Europe at the behest of European and American interests. Acheson's
idea was that if the US provides military security for the European states, and
sees to it that none attack the other, their desire for military power will
wane over time and a demilitarized Europe will no longer pose a threat to the
US. And that is pretty much what has happened, despite the complication of the
Cold War and other distractions.


Chris Mark