Since becoming Secretary of State, Condoleezza Rice has been a rare star in a Bush administration that has otherwise stumbled from one mess to another. The reason is not merely her style and dazzling fashion sense. European governments have been impressed by her efforts to restore the role of diplomacy in American policy-making, and to re-establish the primacy of the State Department (as opposed to the Pentagon and the Vice-President's office) in that process.

In less than a year in the job, she has set a blistering travel pace that puts her immediate predecessor, Colin Powell, to shame. In the Middle East last month, she even evoked shades of Henry Kissinger, tearing up her schedule in order to broker personally a critical border control deal for the Gaza Strip. America, it seemed, was once again listening to the world, rather than lecturing it.

This week, however, will provide the sternest test yet of Ms Rice's diplomatic mettle. For the first time, she will be facing a sceptical audience of Europeans, deeply concerned by recent allegations about US "rendition" flights ferrying detainees to face torture or illegal imprisonment and of secret CIA prison camps in eastern Europe operating in flagrant violation of international law. Making matters worse is the seemingly equivocal attitude of the Bush administration to what the rest of the world understands as torture, pure and simple.

Yesterday, she gave a taste of her tactics. Tired of incessant pummelling, Washington is now hitting back. The fight against terrorism is a dangerous and dirty business, which we are all in together. Rather than indulge in self-righteous sniping from the sidelines, she will be saying that US allies should play their full part in dealing with a global threat that respects no borders.

But the test will be not only in what Ms Rice says, but in how she says it. By all appearances, the short move from the White House to the State Department has been a liberation for her. It would be a pity now if she retreats into the uptight and preachy style that marked her none-too-successful tenure as Mr Bush's national security adviser.

Relations between Europe and the United States are at a crucial juncture. Badly handled, the row over renditions and torture could nullify much of the painstaking work on both sides of the Atlantic to mend fences broken over Iraq. A bullying performance now by the Secretary of State - Condoleezza Rice as Donald Rumsfeld - would be a disaster. We hope the hectoring which she indulged in before take-off yesterday, at Andrews Air Force base, was merely Phase One. Otherwise, the world will only be more convinced than ever that the US has something to hide.