Military power is sustained, in the final result, by economic power. If the latter crumbles, so eventually will the former. - Paul Kennedy

Nothing has ever existed like this disparity of power; nothing. I have returned to all of the comparative defence spending and military personnel statistics over the past 500 years that I compiled in The Rise and Fall of the Great Powers, and no other nation comes close. The Pax Britannica was run on the cheap, Britain's army was much smaller than European armies, and even the Royal Navy was equal only to the next two navies – right now all the other navies in the world combined could not dent American maritime supremacy.

Imperial overstretch has rarely occurred because a great power had too little military force; on the contrary, it was likely still to possess massive forces and at times to deploy them a long way from home. The real problem, it seems, has not been the force-projection capacities of the current number one, but a failure to recognise that long-term wealth and strength depend on the non-military dimensions of national power and on making hard political decisions on the home front.

The Enterprise is a vessel that defies the landlubber's imagination. It is more than 1,100ft long and its flight deck is 250ft across. It is as high as a 20-storey building... But this super-dreadnought never travels alone. It is always accompanied, at the very least, by an Aegis-type cruiser, a large surface ship designed to shoot down incoming missiles; by a bevy of frigates and destroyers to protect it from enemy submarines; by a lurking hunter-killer submarine or two; and by some supply vessels and other specialised craft. Marine troops and their helicopters will be in the task force. In offensive and defensive terms, this is a behemoth... What is more, no equivalent concentration of power to a US carrier task force exists in the world; the few UK, French and Indian carriers are minuscule by comparison, the Russian ones rusting away.