The number of ships a country possesses has never been the sole measure of its power at sea. Other factors, of course, play a role: The types of ships it has—submarines, aircraft carriers, destroyers—the manner in which they are deployed, the sophistication of their sensors, and the range and lethality of their weapons all make a difference. Still, on the high seas, quantity has a quality all its own. And over the past several decades, U.S. ship numbers have seen a dramatic overall decline.
