An aircraft carrier is a potent tool for force projection, a mobile air base to provide airpower wherever it is needed.
The Royal Navy refers to the new carrier HMS Queen Elizabeth as "four acres of sovereign territory, deployable across the globe to serve the United Kingdom", and other nations measure their strength by the number of carriers they can operate.
However, aircraft carriers are part of a bigger picture and they are far from invulnerable.
It can carry out attack missions without being spotted by surface-to-air missiles operators, and in air-to-air combat an F-35 pilot will see the enemy first, and can choose to evade or attack before the opposition is even aware they are there.
Queen Elizabeth will initially host 24 F-35Bs (one squadron) but could eventually have at least twice that number.
An entire squadron will be able to get airborne in just 15 minutes via the ski jump ramp.
HMS Queen Elizabeth will also have a complement of helicopters, the mix depending on the mission.
For blue-water operations, these might include Merlin anti-submarine helicopters as well as Merlin Crowsnest airborne early warning helicopters.
If the requirement is to support land operations, then the helicopter fleet could comprise Chinook heavy transports, Apache gunships and Lynx Wildcat multirole helicopters.
The contrast between the two ships says something about the approach of the two nations.
And, while there continues to be debate in the UK over whether the £3.1bn cost of Queen Elizabeth is good value, the £10bn price tag for the latest US carrier went practically without comment.
Air power is a key component of modern warfare. In a sense, whoever controls the air controls the land or sea below.
Hence the ability to sail a carrier to any trouble spot makes it a vital tool in projecting power.
But the dominance of aircraft carriers has of course led to weapons to sink them.
These ‘carrier killers’ include submarines like Russia’s Antey-class, cruisers and corvettes packed with guided missiles, and, more recently China’s giant DF-21 and DF-26, land-based ballistic missiles with a range of more than 2,000 miles specifically designed to target ships.
A one-tonne warhead moving at several thousand miles an hour could do huge damage even to something the size of an aircraft carrier.
Queen Elizabeth has limited defensive armament – a trio of ‘Dalek’ computer-controlled guns for shooting down incoming missiles at close range – plus a decoy system which launches countermeasures which can confuse both missiles above the water and torpedoes below it.
However, an aircraft carrier will never sail alone, but will be escorted by other ships as part of a carrier strike group.
HMS Queen Elizabeth and will typically be accompanied by several Type 45 destroyers and Type 23 frigates, as well as one or more Astute-class hunter-killer submarines.
These will deal with any incoming threats, whether they are enemy ships, aircraft, missiles or submarines.
In recent conflicts, aircraft carriers have been able to stay well away from the conflict zone, sending their squadrons to bomb relatively unequal opponents.