The US army and marines have had a good run for the taxpayers' money in recent decades with their armed social work; now it is the turn of the air force and navy, especially since Obama has decided that the US is in the Pacific for the long haul. You don't need paratroops and tanks — or indeed armed social workers — to take on the Chinese, but sophisticated cyberweapons of the kind they are developing. Obama should revisit the US military presence in Europe, and make the locals pay for their own defence after freeloading on the US since 1945. Containment of Iran's ballistic missile threat could be done better from Saudi Arabia or Turkey than from the Czech Republic or Poland, and without undermining the Russians' own nuclear deterrent. US oil and natural gas self-sufficiency is also likely to lead to a radical reconsideration of US involvements in the Middle East, where it gets precious little thanks.

Obama is also correct in emphasising the need to repair the US economy and education system, the priority of the 2010 National Security Strategy document. For the US is only "declining" in the sense that others are swiftly rising. China will probably become the world's major economy by 2016-18 and its defence spending will surpass that of the US by 2025. The problem is how to entice China outside its own northern Pacific sphere of influence to assume global burdens commensurate with its responsibilities and size. That role may be forced upon Beijing, judging by the swift evacuation of 35,000 oil workers from Libya late last year. What happens if Chinese workers are roughed up in Zambia?

Obama has also acknowledged altered economic realities by making the G20 the main forum of global decision-making instead of the defunct G8. In the post Cold War world, Brazil, India, Indonesia, South Africa and Turkey really count. Ironically, the demise of a cosy Western club is likely to see the emergence of much more cautious diplomatic initiatives, which will be favoured by Western voters weary of the "piratical" unilateral interventionism (the phrase is Sir Vidia Naipaul's) of Bush and Blair. The world that has emerged — an approximate reversion to what it looked like in about 1890 — is what the majority of people seem to want. As the saying goes, be careful what you wish for.