The biggest change in my time in politics has been the degree to which a problem in one part of the world far from us can have a direct impact on Britain and the British people. Afghanistan has reminded us what happens if we turn our back on a problem and has also demonstrated how dangerous the world has become.

If India and Pakistan, both nuclear powers, went to war, it would affect us here on our streets. If a conflict in the Middle East makes the whole region unstable, we would see the consequences here in the price of petrol at the pumps and in the effect it would have on our jobs and industry. If Afghanistan were again to become a haven for terrorism, we would not be immune, as September 11 showed.

In the new interdependent world, terrorists from several countries, trained in Afghanistan, brought terror to the streets of America. We acted in Afghanistan not just to hold to account those responsible but also to prevent further planned outrages around the world. And despite the immense problems of any military operation in a country like Afghanistan, underlined by the deaths of the US servicemen on Monday [4 March 2002], we have made great progress towards our goals.

Al Qaeda and other international terrorists remain a serious threat but we always made clear that the action against Al Qaeda and their Taliban allies in Afghanistan was only the first stage in the war against terror.

What we now have to face is the fact that there are irresponsible states which either have, or are actively seeking, biological, chemical and nuclear weapons. This is the threat which President Bush rightly highlighted in his State of the Union speech.

We know, for instance, from his own history that Saddam Hussein, the Iraqi leader, has mass destruction weapons and will use them. He has an appalling track record of terror and aggression against his own people and neighbouring states, including the unprovoked invasion of Kuwait.

Saddam not only used chemical weapons repeatedly against Iranian soldiers, but against his own citizens when he attacked Kurds in northern Iraq. This is why, as a condition of the ceasefire at the end of the Gulf War, the United Nations demanded -- and Saddam agreed -- that its representatives should be allowed into Iraq to dismantle his weapons of mass destruction and ensure he did not replace them.

Before he kicked out the UN weapons inspectors three years ago, they had discovered and destroyed thousands of chemical and biological weapons, including thousands of litres of anthrax and 48 missiles. These were weapons he always denied having.

The UN inspectors were also convinced he had hidden other deadly arsenals and the plants to manufacture more but, because of his almost daily obstruction of their work, they could not track them down. As they got closer, they were told to get out of Iraq.

So it is important we remain vigilant about the threat he poses. IF we fail to continue to restrain Saddam Hussein, what is already a volatile situation in the region could easily become a world crisis. Guarding against that and dealing with this threat matters to this country: to British lives; to British security; to British prosperity.

Just because we have managed to contain the threat from Saddam for so long does not mean it has gone away. Saddam is continuing his chemical and biological weapons programmes and is developing the long-range missiles to deliver them. This explains why the international community is so determined to get UN inspectors back into Iraq and to make it possible for them to do their job without obstruction.

How we act is a matter for discussion. Though Iraq seems far away and Saddam, for the moment, is on the defensive, it is in the interest of us all to face up to these threats with determination and resolve.

Effective foreign policy and UK stability have never been more closely linked. There aren't faraway problems that have nothing to do with Britain. In today's world, they are our problems and they are capable of hurting us if we don't deal with them and helping us if we do.

What the lessons of America's leadership following September 11 demonstrate is that President Bush will consult widely with his allies. Saddam Hussein would be wise not to mistake this for weakness. He should not underestimate the determination of the international community to prevent him developing and using weapons of mass destruction.