Rupert Cornwell: Could this clash be Obama's 'MacArthur moment'?

What is it about top American military men and laid-back magazines? In early 2008, Admiral William Fallon, then head of US central command, had to resign after suggesting in an interview with Esquire that his was the sole voice of sanity preventing then President George W Bush from invading Iran. But that indiscretion pales beside those delivered to Rolling Stone by General Stanley McChrystal and his aides.

By belittling President Obama, Vice-President Joe Biden and national security adviser James Jones, General McChrystal and his colleagues have broken the unwritten compact between Americans and their military.

The US armed forces enjoy a respect unmatched in almost any other country. In return though they must not be overtly disrespectful or challenging of their commander-in-chief in the Oval Office. Not only has General McChrystal violated that rule, his judgement must also be questioned by allowing his aides to vent in public against their civilian bosses, when one of his junior officers would probably have paid for similar trash-talk against him with his career. It's hard to see how General McChrystal, however important his role at this critical juncture in the Afghan war, can escape similar punishment.

Unhappiness at a president among the top Pentagon brass is nothing new. The most recent example was Bill Clinton in his early years in office. Widely perceived as a Vietnam draft dodger, Mr Clinton was believed by the generals to be "anti-military" – a fact seemingly confirmed by his determination to end the ban on gays in the military, even by his inability to deliver a suitably crisp salute on ceremonial occasions.

Mr Bush, by contrast, loved being with soldiers, even though his avoidance of Vietnam was no less suspicious than that of his predecessor. Mr Obama, for his part, seemed to be greeted with a wary respect by the generals, and on Afghanistan has been anything but a dove, granting General McChrystal his surge in Afghanistan last autumn.

Now Mr Obama may be facing his "MacArthur moment". The most dramatic clash between a US general and his commander-in-chief came in April 1951, at the height of the Korean War, when Harry Truman sacked Douglas MacArthur. After blundering by provoking China to join the war alongside North Korea, Genera MacArthur pressed for total victory, even if it meant using nuclear weapons on China. The White House however had long since decided on "limited war".

General MacArthur was relieved of his supreme command in the Far East on the grounds of insubordination. For a moment the very principle of civilian command of the military seemed at stake. In retrospect, the downfall of General MacArthur sealed a change in Korean policy. If General McChrystal is forced out, a similar moment may be at hand over Afghanistan.