Harry S. Truman was never a friend of communism. In 1941, after Germany invaded Russia, the then-U.S. senator said, “If we see that Germany is winning the war, we ought to help Russia; and if that Russia is winning, we ought to help Germany, and in that way let them kill as many as possible.”

In a letter to his mother and sister, Truman called the Soviets “pigheaded” and difficult to work with, said Sam Rushay, historian and archivist at the Harry S. Truman Presidential Library and Museum in Missouri. But at least one man, however, was different in Truman’s mind, and that was Joseph Stalin, the Soviet Union’s communist leader.

“I can deal with Stalin. He is honest — but smart as hell,” the 33rd president of the United States wrote in a diary entry dated July 17, 1945, the first day of the Potsdam Conference in Germany. Truman was meeting with his fellow Allied leaders — Stalin and British Prime Minister Winston Churchill — to negotiate the terms of the end of World War II. Germany had surrendered about two months earlier, and the leaders needed to agree on postwar reparations from the country.