SILENCE is a powerful mark of respect. There have been so many words and so many pictures; there has been so much anguish, so much heart-rending.

But a short silence today allowed for a long reflection on the enormity of what happened in the United States.

Those wordless minutes let us remember those who died in Manhattan, Washington and Pittsburgh.

No one who saw what happened will ever be able to forget, but the formal silence was a powerful way of stilling the world for a moment and remembering.

After this short, poignant silence the time for action returns. For those on the ground in New York, the grim activity of sifting through the hellish aftermath of catastrophe continues.

There have been moments of optimism amid the despondency, such as the five firefighters pulled alive from the rubble of the World Trade Centre. But such occasions are rare and hope of finding many other survivors must be fading.

This is a time for politicians around the world to decide how to act in what for now at least is an almost universal resolve to destroy terrorism wherever it lurks. President Bush speaks of his country's fight against the perpetrators of "the first war of the 21st century", adding in his own way: "I am a loving guy but I have a job to do and I intend to do it."

Backing for Mr Bush has come from around the world, bringing together the most unlikely of allies: China, Russia, Pakistan, Saudi Arabia, Japan and Italy - all have pledged support, along, of course, with Britain, the US's strongest ally.

America deserves every sympathy and should be supported in taking the necessary measures to seek out and punish the culprits. But as ever, caution is required: the unleashing of a sorrowful and angry superpower is a frightening prospect for the world. America's friends must offer both help and wise words.

Indiscriminate and ill-considered revenge would only make an appalling situation even worse.

Updated: 11:11 Friday, September 14, 2001