That means a growing section of the Pacific Ocean — where the United States has operated unchallenged since the naval battles of World War II — is once again contested territory, with Chinese warships and aircraft regularly bumping up against those of the United States and its allies.

To prevail in these waters, according to officials and analysts who scrutinize Chinese military developments, China does not need a military that can defeat the United States outright but merely one that can make intervention in the region too costly for Washington to contemplate. Many analysts say Beijing has already achieved that goal.

To do so, it has developed “anti-access” capabilities that use radar, satellites and missiles to neutralize the decisive edge that America’s powerful aircraft carrier strike groups have enjoyed. It is also rapidly expanding its naval forces with the goal of deploying a “blue water” navy that would allow it to defend its growing interests beyond its coastal waters.