Suppose a war with China, precipitated by a mainland attack on Taiwan. Our principal battle platform, on current doctrine, would be our carrier fleet. (We can not count on any of our regional allies to allow us to attack China from their territory.) With the carriers we would hope to destroy the Chinese air force and missile launching sites, crippling their ability to invade.

How long would that take?

About four hours. Not four hours to win but four hours—at most–to lose our entire carrier fleet in which we have invested at least half a trillion dollars.

That four-hour lifespan is based on experience.

[Actually, I suspect our principal platform for force projection would be submarines and long-range land-based airpower. However, Richard makes an excellent point about the vulnerability of reliance on carriers against well-equipped military opponents, which was even true in the heyday of carriers in WWII. — Ed]