LAST week's terrorist attacks have created a wave of emotions in the United States.

In responding to these emotions and the clamour for retribution, President Bush has resorted to the rhetoric of war.

In offering the unstinting support expected of a staunch ally, our Prime Minister has responded in kind.

It is the duty of a true friend to display unswerving support in public. In private, it is the duty of a true friend to counsel wisely.

While in public Tony Blair may be joining President Bush in the emotive reference to a war on terrorism, in private his language will be more tempered.

We were given an indication of that by Jack Straw and Clare Short yesterday. Both urged caution and restraint to be exercised. Their counsel, though it may not appeal to popular opinion in the US, is wise.

In the wake of the horrific events on Tuesday there has emerged an international unity of purpose unprecedented in history.

Even fanatical opponents of America have condemned the attacks on innocent civilians, and promised to join the campaign to root out terrorists and bring them to justice.

We must not underestimate the potency of such collaboration, which has prompted a regime as extreme as the Taliban in Afghanistan to consider washing its hands of Osama bin Laden.

Having gathered so much sympathy and support as the victim of terrorism, the United States must not risk losing sympathy and support in pursuit of retribution.

If it is clear that the American military response is specifically targeted at smoking out terrorists and those who harbour them, then the mood of collaboration will remain intact.

But if the level of response is excessive, driven by a desire for revenge rather than justice, then the coalition will disperse as quickly as it came together.

The onus on President Bush is to determine the balance between the demands of the American people and the demands of opinion across the world.

The onus on Mr Blair is to offer the President dispassionate advice on how that balance can be struck.