It was possible to discern some embarrassment in President Barack Obama's body language as he stepped up to the dais yesterday in Oslo to accept the 2009 Nobel Peace Prize. One suspects that if Mr Obama had his time over again he would refuse the award on the grounds of it being simply too early for him to accept such a significant prize.

But in the end, the US President gave a speech that showed why the Nobel prize committee must have thought of him in the first place. This was a typically eloquent address full of Mr Obama's moral understanding and his willingness to consider opposite points of view. Yes, he argued, it was necessary to wage war to tackle evil and even intervene in other countries on humanitarian grounds, but, no, he understood the position of those who maintained that war was inherently undesirable.

As America's Commander-in-Chief he reserved the right to undertake military action unilaterally in defence of his country but he argued that wars internationally should be pursued in alliance with others. He appreciated the courage of the soldier who fought for a cause, but sympathised too with those who thought it abhorrent.

He excoriated those such as Burma and Sudan who oppressed their own people but nevertheless argued that it was right to treat with them. And to his credit, he confronted squarely the somewhat awkward co-incidence of accepting a peace prize while raising the US troop commitment in Afghanistan.

It was a fine speech, made all the better by Mr Obama's re-inforcement of his commitment to observe the highest standards while waging war and doing so with the maximum of international support. But in the end it was also a defensive one. Mr Obama arrived in the Oval Office in January with the right mixture of idealism and pragmatism to restore America's reputation in the world. But words alone will not do the job. The real tests of Mr Obama's mettle are still to come. And only when he has passed through such trials will Mr Obama be able to demonstrate that he truly merited yesterday's prize.