AdvertisementWith 'America First,' Trump Challenges The World Constructed After World War IIJune 18, 2018Greg MyrefacebookEmailPresident Harry Truman calls NATO a "shield against aggression" at the ceremony that established the 12-nation alliance in Washington in 1949. Truman played a central role in creating many of the international organizations set up in the wake of World War II. President Trump has often questioned their relevance and cost under his "America First" policy. (AP)