After World War II, the US Navy confronted the challenge of adapting to dramatically altered geopolitical circumstances. Moscow did not have an ocean-going fleet, and early Cold War strategy was dominated by the salient position of nuclear strategic bombing - a mission thought to be outside the purview of the navy. Traditional roles, such as protecting sea lines of communication and supporting ground forces ashore, quickly proved indispensable. However, the navy eventually also succeeded in fielding dramatic technological and institutional innovations, for example, the strategic missile submarine, which enabled the US to successfully leverage maritime power against the continental power of the USSR.