By Paul Reynolds BBC News Online world affairs correspondent

Britain's Foreign Secretary Jack Straw has said that the chances of war with Iraq have fallen from 60:40 in favour to 40:60.

But the language he used in an important speech to a mass gathering of British ambassadors in London indicates that he is preparing the groundwork to justify a war.

And in any case, do not rely on those odds. Mr Straw himself added that they could change from "day to day".

Jack Straw's speech used language similar to that of the Americans

He was, after all, speaking before Saddam Hussein's latest belligerent speech. Maybe the odds have already moved again.

To start with, Mr Straw emphasised - for the first time - the potential threat of a terrorist group like al-Qaeda getting weapons of mass destruction from what he called "rogue regimes".

This is the kind of language previously used by the Americans. It could be used to justify action even if no actual link is found, as it has not been, between Iraq and al-Qaeda.

Verdict reached

Mr Straw also said that Iraq had to disarm. His actual words were: "Iraqi disarmament - whether it is achieved by peaceful means or by force - is essential."

Saddam Hussein referred to the UN weapons inspectors as spies

Note that he does not say: "Wait until the inspectors tell us if Iraq has illegal arms". The verdict is already in.

That again, is the US position.

In fact, Washington has already declared Iraq to be in "material breach" of UN resolution 1441 for giving a "false" declaration of its arms programmes.

It is arguable that it is "heads I win, tails you lose" for the US and UK now.

If the inspectors find nothing, they could argue that Saddam has successfully hidden his weapons; if they find something, their case is proved.

'Associates of Satan'

If it were not so serious, Saddam Hussein's speech to mark Armed Forces Day could be the source of some inspiration to students of rhetoric.

There is the splendid attack on the pronouncements of his enemies as "the hiss of snakes and the bark of dogs".

Saddam praised his soldiers, telling them they could not lose

Comparing his opponents to animals is a frequent device. US and UK aircraft enforcing the no-fly zones are usually referred to as "ravens".

There is the colourful reference to Iraq's "desperate enemies - the friends and wicked associates of Satan, the inhabitants of night and the dark" and his rallying call to his own side: "Their arrows will go astray and your arrows will hit them".

Talk of arrows might not instil his own side with confidence, however, given that arrows are no longer the weapon of choice in war.

But perhaps his troops will understand the message.

Miscalculations

The most significant and worrying part of Saddam's speech was when he referred to the UN weapons inspectors as spies, engaged in "purely intelligence work".

If he really believes this, he might at some stage think that he has nothing to lose by throwing the inspectors out.

He could argue that war is inevitable, so why give the inspectors time to find out Iraqi dispositions. If that happened, war would indeed follow.

Saddam remains hard to read and although he is often called a "survivor" by experts who say that he will do what is necessary to avoid a war to remove him, he is also a fighter who has made miscalculations before.

His war against Iran launched in 1979 was disastrous. So was his invasion of Kuwait in 1990.

Despite Mr Straw's effort to act as the friendly bookmaker, the signs are still pointing to war.