Jack Straw: 'I joined the peace protesters in the Sixties. Believe me, this is different'

The removal of the threat of force in Iraq would open up an even greater danger to the region

As a young participant of peace protests in the early 1960s, I recognise the strong emotions that drove so many people to join last weekend's "Stop the War" march in London. When I marched from Aldermaston 40 years ago, I did so in the belief that the case was a moral one, and I still believe it was. I have always acknowledged the logic of those who argue that military action can never be justified, UN resolutions or not. I find it more difficult, however, to fully understand the logic of the non-pacifist case against the potential use of force against Iraq.

It seems to me there are three main arguments. One is to argue that the Iraqi regime does not possess any weapons of mass destruction. The second is that Iraq is not the only regime possessing these terrible weapons. The third is that Saddam Hussein can be permanently contained by inspection. I want to deal with each in turn.

To believe that Iraq has no such weaponry demands a degree of trust in Saddam Hussein which he has done nothing to earn. Take his biological weapons programme. For four years after his expulsion from Kuwait, Saddam insisted he had no such programme at all, and the UN inspectors could find no evidence to contradict him. It was only when his son-in-law, Hussein Kamil, defected to Jordan and told all in 1995 that the full extent of Saddam's production of anthrax, botulinum toxin and aflatoxin became clear. Later lured back to Iraq with a promise of an amnesty, Saddam's son-in-law paid for his confession with his life. (No wonder Iraqi scientists today are not too keen on offering unvarnished evidence to the inspectors.)

The pattern of deceit by Saddam continues. UN Security Council resolution 1441, unanimously agreed last November, gave Saddam a "final opportunity" to comply with the United Nations. Yet in his response issued in December he again said he had no weapons of mass destruction. Crucially, he offered no explanation as to the whereabouts of the vast amount of horrendous weaponry, including 1.5 tonnes of VX nerve agent and large quantities of growth media required for biological weapons, unaccounted for at the time when the UN inspectors were effectively forced to leave Iraq in 1998. In the words of Dr Hans Blix, head of today's UN weapons inspection team, this is a "significant outstanding issue of substance".

Dr Blix has also described as "of great significance" Iraq's failure to account for 1,000 tonnes of chemical agent, and has added that there were indications that VX – one of the deadliest nerve agents known to man – had been turned into a weapon. According to Dr Blix, there are "strong indications" that Iraq has retained some anthrax, despite the claims to have destroyed the 8,500 litres it admits to having produced; and has developed missile systems capable of exceeding the range laid down by the UN and which use engines imported in contravention of UN sanctions.

It is, therefore, hard to make a case that this is a regime that deserves the benefit of the doubt. As Dr Blix himself said last month, Iraq "appears not to have come to a genuine acceptance ... of the disarmament which was demanded of it". If we are to believe Saddam has no weapons of mass destruction, we must disbelieve all the evidence of systematic concealment and deception, disregard the reports of the UN weapons inspectors – and, I would add, must put more faith in Saddam's word than in that of democratic governments.

The second argument for opposing military action is that Iraq is not the only regime to possess weapons of mass destruction. There are, indeed, other countries which have developed chemical and biological weapons, and there are serious concerns about North Korea's nuclear weapons programme. All of this should worry us greatly. Such weapons are capable of inflicting immense suffering, and in the hands of terrorists could threaten our own cities. Stopping the proliferation of such technology must be a key priority for the international community for years to come. One difference is that the diplomatic routes – always preferable – to a solution in North Korea have still not been exhausted.

But Iraq is unique in having not only a WMD capability but also the proven appetite to use them. It was Saddam who used chemical weapons to kill thousands of Iranians and Kurds in the 1980s. At the time of the Gulf War, he was within three years of having nuclear arms. Such weapons are integral to a regime that has routinely used murder, torture and rape as a means of maintaining control in Iraq; which has invaded two of its neighbours and fired missiles against five of them. Our intelligence shows that, even today, Saddam regards his poisons and diseases not as weapons of last resort but as active parts of his arsenal of terror.

On 3 April 1991, the UN Security Council imposed a legally binding obligation on Iraq to give up its weapons of mass destruction within 90 days. Twelve years and countless further UN resolutions on, a failure to disarm Iraq now would send a very clear message to every other tyrant that the will of the international community can be broken.

The third argument against military action accepts that Iraq may still have weapons of mass destruction, but suggests that the mere presence of inspectors means that Saddam can be permanently contained.

The inspectors will have more time, and Dr Blix is due to report again to the Security Council soon. But the inspectors are not a detective agency charged with seeking out Saddam's weapons. That was not what UNSC resolution 1441 was about. Indeed, the chance that 300, or even 3,000, inspectors could criss-cross a country the size of France and successfully track down substances capable of being produced in an ordinary living room is absurd.

The inspectors are there to verify the Iraqis' own surrender of this weaponry and its destruction, and to fulfil their mandate they require full and active co-operation from Iraq akin to that offered by South Africa when it abandoned its nuclear weapons programme at the end of apartheid. And for all the grudging "help" that Saddam is offering on relatively trivial details of the process, there is no significant evidence that he has finally decided to accept these legal obligations imposed upon him by the United Nations.

To remove the threat of force at a time when Iraq continues to violate its international responsibilities would be a bad mistake. Saddam would be emboldened, would bide his time and would continue to deny and deceive. He would hope – with some justification – that as time went by, the international community's focus would eventually be averted elsewhere and that, in the end, life would be made so difficult for inspectors that they would leave. That is what happened before, and will happen again if we believe that containment is a policy worth pursuing indefinitely. A Saddam who had once again flouted the will of the UN would be a more dangerous Saddam, both to his neighbours and to his own people.

Even at this late stage, I hope and pray war can be avoided. But without the credible threat of force, which the US and ourselves have ensured, there would be no inspectors in Iraq today, and the removal of that threat now would open up an even greater danger to the region. It has never been more vital than now that the international community comes together to uphold the authority of the United Nations and to enhance the cause of peace and security in Iraq and elsewhere.