Following WWII, Europe and Asia underwent significant changes - Germany and Berlin were divided between the Western allies and Soviet Union, while the US took sole responsibility for rebuilding Japan and establishing a new democratic constitution under General Douglas MacArthur. Meanwhile, the Cold War emerged between the capitalist West led by the US and the communist Eastern Bloc led by the Soviet Union, which exerted control over countries behind the Iron Curtain and cut off access to West Berlin until the US launched a massive airlift of supplies; this instability continued with the outbreak of the Korean War as North Korea invaded South Korea across the 38th Parallel boundary.