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.
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.