The North Atlantic Treaty, creating the defense alliance of NATO, was signed in April 1949, but required Senate ratification. The vote for this came in July. Senator Robert A. Taft—the effective leader of the Republican Party in the Senate—announced his intention to oppose the treaty and, after it passed, made another speech criticizing it. One can read the speech as an example of the isolationist, “fortress America” approach to foreign policy that leaders like Taft and former President Hoover espoused. Many viewed Taft’s view as outmoded by the post-World War II reality of an expansionist Soviet Union, and the isolationist character of Taft’s thinking helped defeat his runs for the Republican presidential nomination in 1948 and 1952. However, Taft’s speech merits reading for the contrast he draws between the North Atlantic Treaty and the Monroe Doctrine, an earlier assertion of the US intent to defend its foreign interests against any attempt by a major power to expand its empire. Taft’s critique details how much further the United States would now go to protect allies, as well as how much firmer the commitment we were now willing to make.