On the morning of September 11, 2001, America’s prospects appeared as bright as the clear blue sky over Lower Manhattan. The price of Brent crude oil was $28 a barrel, the Federal government was running a budget surplus, the US economy was turning (albeit imperceptibly) after the dotcom crash. The most powerful nation on earth was at peace.

Ten years on, the oil price hovers around $115 a barrel, the US is projected to run a budget deficit for 2011 of $1,580bn, the largest in its history; the economy remains deeply troubled after the financial crash of 2008; and America’s military and intelligence services remain at war, battling insurgency and radical Islamic terrorism, from Afghanistan and Pakistan to Niger and Yemen.

Admiral William Mullen, outgoing chairman of the Joint Chiefs of Staff, has described the national debt as the greatest threat to US national security. Standard & Poor’s recent downgrade of America’s credit rating appears to confirm the superpower’s steady slippage. And while there is no linear narrative from the September 2001 attacks to America’s present economic plight, the inflation-adjusted cost of the ensuing “global war on terror” at more than $2,000bn amounts to twice the cost of the Vietnam war.