Claim: The United States became the only country to have used nuclear weapons in warfare when they dropped atomic bombs on Japan during World War II.
Evidence: The United States emerged from as a global superpower , the first country to develop nuclear weapons , the only country to use them in warfare , and a permanent member of the United Nations Security Council.
At the order of President Harry S. Truman during the final stage of World War II , the United States dropped nuclear weapons on the Japanese cities of Hiroshima and Nagasaki on August 6 and 9 , 1945 , respectively.