Albert Einstein Einstein did not return to Germany. He settled in the United States and became an American citizen in 1940. On the eve of World War II, he endorsed a letter to President Franklin D. Roosevelt alerting him to the potential development of "extremely powerful bombs of a new type" and recommending that the US begin similar research. This eventually led to the Manhattan Project. Einstein supported the Allies, but he generally denounced the idea of using nuclear fission as a weapon. He signed the Russell–Einstein Manifesto with British philosopher Bertrand Russell, which highlighted the danger of nuclear weapons. He was
Political views of Albert Einstein as a means for the solution of international conflicts. Nevertheless, it is, in my opinion, not reasonable to cling to that principle unconditionally. An exception has necessarily to be made if a hostile power threatens wholesale destruction of one's own group. Following the conclusion of World War II, Einstein once again became a constant and vocal activist for world peace. Political views of Albert Einstein Albert Einstein was widely known during his lifetime for his work with the theory of relativity and physics in general. He was also an important peace activist, a world federalist and a socialist. His political