In the aftermath of the Second World War, the British Empire declined, leaving the U.S. and USSR as the dominant world powers. Tensions among these former Allies grew, resulting in the Cold War. Although Stalin publicly described the British and U.S. governments as aggressive, he thought it unlikely that a war with them would be imminent, believing that several decades of peace was likely. He nevertheless secretly intensified Soviet research into nuclear weaponry, intent on creating an atom bomb. Still, Stalin foresaw the undesirability of a nuclear conflict, saying in 1949 that "atomic weapons can hardly be used without spelling the end of the world." He personally took a keen interest in the development of the weapon. In August 1949, the bomb was successfully tested in the deserts outside Semipalatinsk in Kazakhstan. Stalin also initiated a new military build-up; the Soviet army was expanded from 2.9 million soldiers, as it stood in 1949, to 5.8 million by 1953.