Leading article: An escalating and irresponsible war of ill-considered words

Which makes it, in the most obvious sense, doubly stupid for the new Iranian leader to have given ammunition to his foes in this fashion and - more important, perhaps - greatly embarrass Iran's allies on the Security Council such as Russia. If London and Washington, with support from Paris, are now intent on isolating Iran in the world, and facing them with united UN sanctions, Mr Ahmadinejad could hardly have done more to further their cause.

Did he know what he was doing, or, as some commentators suggest, were the remarks the ill-considered outburst of an inexperienced zealot? It's a difficult, but all-important, question. That Mr Ahmadinejad is a religious fundamentalist anxious to return to the pure doctrines of Ayatollah Khomeini should not be in doubt. But his election seems to have left the Iranian clerical and political establishment as surprised as the world outside.

Since he took office, Iran's spiritual leader Ayatollah Ali Khamenei has moved to clip his wings through the Expediency Council under Akbar Hashemi-Rafsanjani. Mr Ahmadinejad's election represents a hardening of Iran's nationalistic stance, especially on the nuclear issue, but it does not necessarily represent a complete change in foreign policy.

Just as uncertain are the intentions behind the recent hardening in the rhetoric of George Bush and Tony Blair. Although the Foreign Secretary, Jack Straw, has specifically ruled out military action, President Bush has always been ambiguous on the issue, and Tony Blair seemed almost to be hinting at it on Thursday when he spoke of Iran's actions leading to a point where "the question people will be asking us is: when are you going to do something about Iran?".

This is a form of madness, and grossly irresponsible of the British Prime Minister. Whatever criticisms may be levelled against Tehran, it has the right to develop nuclear power and uranium enrichment for peaceful purposes; it remains a signatory of the Nuclear Non-Proliferation treaty and, as Iraq's largest neighbour and co-religionist, it is bound to take an active interest in developments there.

Not the least fault of Washington in its dealing with Iran has been to try to isolate it early on when it was most willing to co-operate in the immediate aftermath of the overthrow of its most hated enemy, Saddam Hussein. To try to isolate it further now and to seek actively regime change would only drive it into a corner with incalculable results.

The international community cannot allow to go unchallenged public statements by the leader of one state urging the elimination of another. Nor can it ignore any signs of a move by Iran to become the possessor of nuclear weapons. But these are issues which should be resolved in the United Nations and through dialogue, not by adopting the language of dark military threat.