Aircraft carriers, particularly super carriers, have always been very expensive, but they possess a� unique set of capabilities which not only outshine their contending substitutes, their 'existence' also serves as an important foreign policy tool in both peacetime� and war. A carrier battle group is the most visible means to 'show the flag around': it poses as a credible deterrence to any would-be aggressor, and when that fails, it is tasked to conduct combat operations promptly during a crisis response. Furthermore, in the early days of a fast-breaking conflict, land-based tactical aircraft were not able to arrive in sufficient numbers, thus the leading air-support role had to be provided by sea-based aviation. Therefore, land-based aviation can only complement but not substitute sea-based aviation. Super carriers can provide US forces a forward presence without being entangled in bases on foreign territory. Aircraft carriers, regardless of their size, have always been regarded as symbols of prestige, thus providing a strong impetus for medium-sized navies to acquire them.47�However, a small capacity carrier may not be able to conduct effective combat operations. The recent Strategic Defence Review released by the British government, which highlighted the preference for medium-sized carriers as a substitute for its light carriers, reiterates the practicalities of a bigger embarked air wing provided by larger deck carriers. On the other hand, whether the US will maintain a 12-super carrier force level in future will depend on the role it intends to play in the international arena, rather than on the debate on the super carrier's merits and demerits.