Brian Jones: Do we really need 1,000 new spies?

The Home Secretary is expected to announce today that the Security Service (MI5) will be boosted by resources for 1,000 new staff to counter the threat from international terrorism. I have no doubt that my former colleagues in Thames House and the wider UK intelligence community will be greatly encouraged by this move. However, a number of questions arise, and I hope they may be answered in the coming days.

From an intelligence and security perspective, it seems rather odd to so publicise a change to an organisation that normally operates with stealth and in the shadows.

Given that it will take some time to recruit and train the top-quality personnel required, it is unlikely that MI5's capabilities will be greatly enhanced for a year or more. One of two possibilities follows from this: either the threat from international terrorism is expected to grow significantly over the next few years, or this is a tacit admission that current resources are inadequate and of a failure, for whatever reason, to match investment to the existing threat to national security.

If the former is true, it follows that for the past two years we have been losing the war against global terrorism, and that there has been no benefit in this regard from the invasions of Afghanistan and Iraq.

If the latter is the case, then, quite apart from wondering at the wisdom of advertising a vulnerability, we should try to understand why we find ourselves so far behind the curve that such drastic measures are necessary.

There was clearly little perception of the threat we now face when the Prime Minister declared early on his vision of Britain as a force for good in a post-Cold War world, devoid of direct threats to our security. This was despite the sarin attacks by the Aum Shinrikyo sect in Japan a year or so earlier, which many described at the time as a "wake-up call", and growing evidence through the 1990s of other terrorists' interest in "weapons of mass destruction".

Perhaps right up to 11 September, there was a complacency bred of familiarity with the activities of the Provisional IRA that prevented the Home Office from recognising that terrorism could or would be conducted on a grander scale. This seems to have been the case, judging by the Prime Minister's interview with The News of the World last weekend: "11 September showed us a new type of terrorism, completely different, say, from the IRA... the IRA would not have tried to kill 3,000."

It seems that certain critical messages may not have been reaching the upper echelons of government. One is reminded of Jonathan Powell's belated recognition of the argument expounded in these pages by Donald Macintyre with regard to the Iraq dossier, that a chemical or biological weapons threat would only be created if we attacked Saddam. Something very similar appears to be happening with respect to terrorism and the widespread perception of the west in general, and the UK in particular, as an enemy.

In the immediate aftermath of 11 September, Mr Blair acknowledged the need to take account of the poverty and sensitivities of those we might otherwise drive into the arms of terrorists. But since then it has been difficult to discern signs of balance in the Government's approach to the threat of the unconstrained global terrorist. Our unconditional support of the US in its wars on Afghanistan and Iraq, and its imprisonment of terror suspects in Guantanamo Bay, can only have been provocative. It may be that a more balanced political approach could be as effective in reducing the risk as the proposed investment in MI5.

This does not mean that the two elements are mutually exclusive. Indeed an investment of 1,000 staff does not strike me as excessive. Though to increase the size of an organisation by 50 per cent does sound somewhat arbitrary, and I wonder whether the threat has been clearly enough defined to recruit and deploy the new resources to the greatest effect.

The primary concern seems to be with the "new type" of terrorists' desire to create chaos in the west by killing thousands of people. This has led Mr Blair, rightly in my view, to couple WMD and international terrorism as the security challenge of the 21st century. I know from my own experience that the pool of nuclear, biological and chemical defence experts in the UK who can contribute to our security is finite, and cannot be quickly expanded. They must therefore be used wisely. Although the culture of MI5 is necessarily different from the rest of the intelligence community, the UK does not have the luxury of spreading the available resources too widely across the various organisations involved. There are competing demands of equal priority outside intelligence for the development and operation of materials, equipment and systems concerned with prevention and consequence management.

Where resources are so limited, it is worrying to see a single "leaked" announcement from one Department of State about a single agency. It must be hoped that other areas are also receiving a boost. The chairman of the Defence Select Committee, Bruce George, has spoken reassuringly about the initiative. If this marks recognition that much of the relevant expertise resides in the defence sector, that is a good sign. It will be interesting to see if stronger evidence emerges of a joined-up approach to what I believe is a vital issue.

The writer was head of the branch of Defence Intelligence Staff responsible for the analysis of intelligence on nuclear, biological and chemical warfare