Barack Obama angry at General Stanley McChrystal speech on Afghanistan

The relationship between President Barack Obama and the commander of Nato forces in Afghanistan has been put under severe strain by Gen Stanley McChrystal's comments on strategy for the war.

According to sources close to the administration, Gen McChrystal shocked and angered presidential advisers with the bluntness of a speech given in London last week.

The next day he was summoned to an awkward 25-minute face-to-face meeting on board Air Force One on the tarmac in Copenhagen, where the president had arrived to tout Chicago's unsuccessful Olympic bid.

When asked on CNN about the commander's public lobbying for more troops, Gen Jim Jones, national security adviser, said:

“Ideally, it's better for military advice to come up through the chain of command.”

Asked if the president had told the general to tone down his remarks, he told CBS: "I wasn't there so I can't answer that question. But it was an opportunity for them to get to know each other a little bit better. I am sure they exchanged direct views."

An adviser to the administration said: "People aren't sure whether McChrystal is being naïve or an upstart. To my mind he doesn't seem ready for this Washington hard-ball and is just speaking his mind too plainly."

In London, Gen McChrystal, who heads the 68,000 US troops in Afghanistan as well as the 100,000 Nato forces, flatly rejected proposals to switch to a strategy more reliant on drone missile strikes and special forces operations against al-Qaeda.

He told the Institute of International and Strategic Studies that the formula, which is favoured by Vice-President Joe Biden, would lead to "Chaos-istan".

When asked whether he would support it, he said: "The short answer is: No."

He went on to say: "Waiting does not prolong a favorable outcome. This effort will not remain winnable indefinitely, and nor will public support."

The remarks have been seen by some in the Obama administration as a barbed reference to the slow pace of debate within the White House.

Gen McChrystal delivered a report on Afghanistan requested by the president on Aug 31, but Mr Obama held only his second "principals meeting" on the issue last week.

He will hold at least one more this week, but a decision on how far to follow Gen McChrystal's recommendation to send 40,000 more US troops will not be made for several weeks.

A military expert said: "They still have working relationship but all in all it's not great for now."

Some commentators regarded the general's London comments as verging on insubordination.

Bruce Ackerman, an expert on constitutional law at Yale University, said in the Washington Post: "As commanding general, McChrystal has no business making such public pronouncements."

He added that it was highly unusual for a senior military officer to "pressure the president in public to adopt his strategy".

Relations between the general and the White House began to sour when his report, which painted a grim picture of the allied mission in Afghanistan, was leaked. White House aides have since briefed against the general's recommendations.

The general has responded with a series of candid interviews as well as the speech. He told Newsweek he was firmly against half measures in Afghanistan: "You can't hope to contain the fire by letting just half the building burn."

As a divide opened up between the military and the White House, senior military figures began criticising the White House for failing to tackle the issue more quickly.

They made no secret of their view that without the vast ground force recommended by Gen McChrystal, the Afghan mission could end in failure and a return to power of the Taliban.

"They want to make sure people know what they asked for if things go wrong," said Lawrence Korb, a former assistant secretary of defence.

Critics also pointed out that before their Copenhagen encounter Mr Obama had only met Gen McChrystal once since his appointment in June.