Strauss believed in a fundamental premise of the Cold War, that the Soviet Union was determined on a course of world domination; as such he believed in having a more powerful nuclear force than the Soviets and in maintaining secrecy about U.S. nuclear activities. This extended to allies: among the commissioners, he was the most skeptical about the value of the Modus Vivendi that was agreed to in January 1948, that provided for limited sharing of technical information between the United States, Britain, and Canada (and that was already a stricter set of guidelines than those established by President Franklin D. Roosevelt in the Quebec Agreement of the Manhattan Project era). During the United States presidential election, 1948, Strauss tried to convince Republican Party nominee Thomas E. Dewey about the dangers of sharing atomic information with Britain, and after Dewey lost, Strauss tried to convince Truman on the same. Following the revelations about the British physicist Klaus Fuchs's espionage for the Soviet Union, and the appointment of the former Marxist John Strachey as Secretary of State for War in the British Cabinet, Strauss argued that the Modus Vivendi should be suspended completely, but no other commissioners wanted to go to that extreme.