The U.S. Navy's surface warships far outnumber those of any possible competitor militarily. In part this is because surface warships are vulnerable militarily so that even nations that can afford them haven't built them. Aircraft and submarines are better alternatives for many military missions.
I have repeatedly posted about indications that surface warships are vulnerable to missile attacks and submarine warfare. There are active anti-submarine and anti-missile systems on every U.S. warship, but when push comes to shove, the information available to the civilian public indicates that surface warships usually lose. Tragedy has been avoided so far, mostly because we have had very few hostile military incidents since World War II with nations that have modern submarine or missile resources. The surface navy is mostly now as group of U.S. military bases that the U.S. doesn't have to receive permission to put in place, for use against opponents too militarily unsophisticated to have modern submarines or anti-ship missiles. And, recent conflicts in and around Israel have established that even well organizized non-sovereign terrorist groups now have access to modern anti-ship missiles.
Another problem with the U.S. Navy is that to get within striking range of a target, your entire self-contained force must be reasonably close to your military opponents. It takes about twenty active duty military personnel to operate an aircraft. But, when you deploy an aircraft to engage an opponent militarily, only a few of those military personnel are exposed to enemy fire from opponents with weapons that have the same range as the aircraft's. In the case of cruise missiles deployed by long range bombing aircraft, the support crew can be a very long distance from the active conflict, even the flight crew doesn't have to get particularly close, and many U.S. bombing aircraft are invisible to (or in the case of cruise missile carrying bombers can stay out of the range of) radar. In contrast, there is no such thing as surface ship stealth, and several hundred crew members must be within striking range, as opposed to one percent of that number of people for an aircraft. Submarines have slightly smaller crews (although still far larger than an aircraft) and are more stealthy than surface ships, of course.
The final problem, shared by both surface ships and submarines, but not aircraft, is speed of deployment and redeployment. Aircraft can be deployed en masse for a major engagement at Okinawa on Monday, and be in place to be deployed in a major engagement in Iraq on Wednesday. Surface ships and and submarines are hard pressed to move 600 miles a day. Their might is available only if military commanders had the foresight to preplace them, and they must be split between all the military theaters where their military capabilities might be needed. This means that, all other things being equal, it takes about a third to a half as many otherwise military equivalent aircraft to meet a global military force requirement as it does naval resources.
Increasingly, the main justification that backers give Congress for U.S. Navy construction is not that the ships are militarily useful, but that they create jobs.
Fortunately, the current administration looks likely to make major cuts in new purchases of surface ships, thereby freeing up fiscal resources for other needs.