Following Chinese military intervention in Korea during late November, Marshall and the Joint Chiefs of Staff sought ways to aid MacArthur while avoiding all-out war with China. In the debate over what to do about China's increased involvement, Marshall opposed a cease–fire on the grounds that it would make the U.S. look weak in China's eyes, leading to demands for future concessions. In addition, Marshall argued that the U.S. had a moral obligation to honor its commitment to South Korea. When British Prime Minister Clement Attlee suggested diplomatic overtures to China, Marshall opposed, arguing that it was impossible to negotiate with the Communist government. In addition, Marshall expressed concern that concessions to China would undermine confidence in the U.S. among its Asian allies, including Japan and the Philippines. When some in Congress favored expanding the war in Korea and confronting China, Marshall argued against a wider war in Korea, continuing instead to stress the importance of containing the Soviet Union during the Cold War battle for primacy in Europe.