- What had changed since Yalta?
- America had a new president which was Harry Truman because Roosevelt had died. This increased tensions between Russia because Truman was very anti-communist.
- Stalin's army was occupying most of Eastern Europe. This made the USA stop trusting Russia.
- The allies tested an atomic bomb at a desert site in the USA. Stalin was informed by Truman. Beforehand the USA didn't tell Russia they where going to test the bomb.