On August 2, 1939, Albert Einstein sent the first of four letters to U.S. President Franklin Roosevelt. Einstein urgently warns Roosevelt of the possibility of the element Uranium being utilized as a highly destructive and devastating bomb. He mentions that Germany has already begun research on such a bomb, making the country a threat. He advises Roosevelt to begin research at once in order to protect the United States from the potential danger of being attacked. Approximately two months later, Roosevelt took Einstein's advice, and gave his approval of the development of the atomic bomb. It was later said that Einstein was sorry that he advised Roosevelt to make the bomb because of the destruction it later caused, but he felt it necessary and didn't regret his decision.