It was more of the personal project of George F. Kennan who wanted a semi-independent Europe holding its own weight, but small states like the Netherlands and Belgium sabotaged it, and France rejected the European Defense Community (Another attempt to subdue France under America).

Since the rest of the Government was already weary of that prospect, Kennan got sacked and the more fragmented approach to Europe became the mores of America.

Of course France had its own ambitions of using Germany and Italy to reestablish itself as a great power. And the UK originally planned to add western europe into the commonwealth of nations.