Owing to the substantial superiority of the Royal Navy's surface forces, Germany's Imperial Navy (in World War I) and Kriegsmarine (in World War II) had little hope of seizing control of the high seas, but with submarines the Germans could hope to defeat the British by choking off their crucial access to seaborne commerce. In both wars, the United Kingdom successfully resisted the German strategy with a combination of strict rationing and the development of anti-submarine weapons and techniques. During the Cold War, the Soviet Union invested heavily in submarines and would likely have pursued a similar strategy of sea denial had tensions with the NATO powers escalated to open warfare.