Here is Dr David Kelly's article, written days before the Iraq war, in which he assessed the threat from Saddam:
In the past week, Iraq has begun destroying its stock of al-Samoud II missiles, missiles that have a range greater than the UN-mandated limit of 150 kilometres. This is presented to the international community as evidence of President Saddam Hussein's compliance with United Nations weapons inspectors.
But Iraq always gave up materials once it was in its interest to do so. Iraq has spent the past 30 years building up an arsenal of weapons of mass destruction (WMD). Although the current threat presented by Iraq militarily is modest, both in terms of conventional and unconventional weapons, it has never given up its intent to develop and stockpile such weapons for both military and terrorist use.
Today Iraq shows superficial co-operation with the inspectorates. Weapons such as 122mm rockets specific for chemical and biological use have been discovered and the destruction of proscribed missiles and associated engines, components and gyroscopes has begun.
Iraq has established two commissions to search for documents and weapons under the direction of Rashid Amer, a former head of Iraq's concealment activities, and a commission has started to recover weapons from Iraq's unilateral destruction sites. [These sites, dating back to 1991, were destroyed by Iraq, illegally, without UN supervision and as part of Iraq's concealment of programmes]. Amer al-Saadi - formerly responsible for conserving Iraq's WMD, now its principal spokesman on its weapons - continues to mislead the international community.
It is difficult to imagine co-operation being properly established unless credible Iraqi officials are put into place by a changed Saddam.
Yet some argue that inspections are working and that more time is required; that increasing the numbers of inspectors would enhance their effectiveness. Others argue that the process is inherently flawed and that disarmament by regime change is the only realistic way forward.
The UN has been attempting to disarm Iraq ever since 1991 and has failed to do so. It is an abject failure of diplomacy with the split between France, China and Russia on the one hand, and Britain and the United States on the other, creating a lack of 'permanent five' unity and resolve. More recently Germany, a temporary yet powerful member of the Security Council, has exacerbated the diplomatic split. The threat of credible military force has forced Saddam Hussein to admit, but not co-operate with, the UN inspectorate. So-called concessions - U2 overflights, the right to interview - were all routine between 1991 and 1998. After 12 unsuccessful years of UN supervision of disarmament, military force regrettably appears to be the only way of finally and conclusively disarming Iraq.
In the years since 1991, during which Unscom and the International Atomic Energy Authority (IAEA) destroyed or rendered harmless all known weapons and capability under UN Security Council Resolution 687, Iraq established an effective concealment and deception organisation which protected many undisclosed assets. In October 2002, Resolution 1441 gave Saddam Hussein an ultimatum to disclose his arsenal within 30 days. He admitted inspectors and, with characteristic guile, provided some concessions, but still refuses to acknowledge the extent of his chemical and biological weapons and associated military and industrial support organisations - 8,500 litres of anthrax VX, 2,160 kilograms of bacterial growth media, 360 tonnes of bulk chemical warfare agent, 6,500 chemical bombs and 30,000 munitions capable of delivering chemical and biological warfare agents remained unaccounted for from activities up to 1991. [Even these figures, it should be noted, are based in no small part on data fabricated by Iraq].
Less easy to determine is the extent of activity undertaken since 1991. In its 12,000-page 'disclosure' submitted to the inspectors in December 2002, Iraq failed to declare any proscribed activities. Today the truly important issues are declaring the extent and scope of the programmes in 1991 and the personalities, 'committees' and organisations involved.
There are indications that the programmes continue.
Iraq continues to develop missile technology, especially fuel propellents and guidance systems for long-range missiles. Iraq has recovered chemical reactors destroyed prior to 1998 for allegedly civilian activity, built biological fermenters and agent dryers, and created transportable production units for biological and chemical agents and the filling of weapons. Key nuclear research and design teams remain in place, even though it is assessed that Iraq is unable to manufacture nuclear weapons unless fissile material is available.
War may now be inevitable. The proportionality and intensity of the conflict will depend on whether regime change or disarmament is the true objective. The US, and whoever willingly assists it, should ensure that the force, strength and strategy used is appropriate to the modest threat that Iraq now poses.
Since some WMD sites have not been unambiguously identified, and may not be neutralised until war is over, a substantial hazard may be encountered. Sites with manufacturing or storage capabilities for chemical or biological weapons may present a danger and much will depend on the way that those facilities are militarily cancelled and subsequently treated.
Some of the chemical and biological weapons deployed in 1991 are still available, albeit on a reduced scale. Aerial bombs and rockets are readily available to be filled with sarin, VX and mustard or botulinum toxin, anthrax spores and smallpox. More sophisticated weaponry, such as spray devices associated with drones or missiles with separating warheads, may be limited in numbers, but would be far more devastating if used.
The threat from Iraq's chemical and biological weapons is, however, unlikely to substantially affect the operational capabilities of US and British troops. Nor is it likely to create massive casualties in adjacent countries. Perhaps the real threat from Iraq today comes from covert use of such weapons against troops or by terrorists against civilian targets worldwide. The link with al-Qaeda is disputed, but is, in any case, not the principal terrorist link of concern. Iraq has long trained and supported terrorist activities and is quite capable of initiating such activity using its security services.
The long-term threat, however, remains Iraq's development to military maturity of weapons of mass destruction - something that only regime change will avert.