The locations of America's carriers has been a fairly controversial subject as of late, with the so-called "carrier gap" causing a short period of time in January, the first since WWII, where no US carrier was deployed overseas.
They can be used as much for responding to disasters and providing humanitarian relief as for offensive capabilities. The old adage goes, when the President is faced with an international crisis overseas his first question is, "Where are the carriers?" Regardless of how truthful that statement remains today, America's supercarriers and amphibious assault ships remain the most complex and potent weapon systems the world has ever seen.