Science has been of great benefit to humankind. But it can also threaten us. The best example of this risk is the threat of nuclear weapons.

Richard Butler, one of the most distinguished diplomats in Australia's history, has just written a book on the nuclear threat: "Fatal Choice: Nuclear Weapons and the Illusion of Missile Defence". Butler has been involved in nuclear disarmament since 1964 and he acknowledges the encouragement given to him by the late Allan McKnight (another distinguished Australian diplomat who, among other things, was the first inspector-general at the International Atomic Energy Agency). Coincidentally, Allan McKnight in retirement and myself co-authored a book two decades ago on nuclear disarmament. It is a small world.

Butler's book has appeared at a critical time. The United States is pulling out of some important arms control agreements and this could lead to an escalation of the arms race with Russia. Meanwhile the tensions between India and Pakistan could lead to a limited nuclear war over Kashmir.

Richard Butler makes several recommendations for dealing with the threat of the spread of nuclear weapons. He suggests that the United States should engage Russia in a major reduction in the strategic nuclear weapons held by both countries and the bring the other nuclear-weapon states into the process of reductions; the United States should cancel the Cold War policy of maintaining nuclear weapons a hair-trigger alert; and the United States should give more attention to stopping the spread of nuclear weapons.

Butler is also critical of the proposed United States National Missile Defence system (what is more popularly known in the media as "Son of Stars Wars"). Butler argues that the system has at least three major problems: the technical problems involved in actually creating a system to knock out in-coming missiles, the high cost of creating and maintaining such a system; and what impact the creation of this system would have on other countries. On the latter point, other countries would also develop their own weapon systems and so there would be a fresh round of the arms race.

Meanwhile, as Butler points out, the September 11 attack on the United States was not done by nuclear weapons. No national missile defence system could have stopped what happened on September 11.

I agree with Butler's book. I would also add some good news. I, too, have been speaking on the nuclear issue since the 1960s. In those days, it was fashionable to speculate on the spread of nuclear weapons and to estimate that by the time of the year 2000 there could be as many as 20 or 30 nuclear weapon states. Australia was on that list back in the 1960s and we now know that there were government discussions about acquiring nuclear weapons. The good news - and there is not much good news in the history of nuclear weapons -is that the number of nuclear weapon states now is not nearly as bad as some of us were predicting three or four decades ago.

An important reason for this good news was the creation in the late 1960s of the Nuclear Non-Proliferation Treaty, which was aimed at stopping the spread of nuclear weapons and obliging current nuclear weapon states to get rid of their stocks. Most countries have agreed to follow that treaty and - as Butler argues so well - it is vital that more be done to ensure its success.

BROADCAST ON FRIDAY 181TH JANUARY 2002 ON RADIO 2GB'S "BRIAN WILSHIRE PROGRAMME" AT 9 PM, AND ON 20TH JANUARY 2002 ON "SUNDAY NIGHT LIVE" AT 10.30 PM