In 1953, the Republican Party's Old Guard presented Eisenhower with a dilemma by insisting he disavow the Yalta Agreements as beyond the constitutional authority of the Executive Branch; however, the death of Joseph Stalin in March 1953 made the matter a moot point. At this time, Eisenhower gave his Chance for Peace speech in which he attempted, unsuccessfully, to forestall the nuclear arms race with the Soviet Union by suggesting multiple opportunities presented by peaceful uses of nuclear materials. Biographer Stephen Ambrose opined that this was the best speech of Eisenhower's presidency. Eisenhower sought to make foreign markets available to American business, saying that it is a "serious and explicit purpose of our foreign policy, the encouragement of a hospitable climate for investment in foreign nations."