Ronald Reagan's star wars programme of the early 1980s was very much a part of a wider right-wing Republican vision of facing down the "evil empire" of the Soviet Union. It also involved a substantial increase in nuclear armaments and a wide-ranging transformation of the US armed forces so that they would be ready and willing to defeat the Soviets in the event of war.
Similarly, the current Bush administration's commitment to missile defence is part of a much wider strategic ambition to ensure "full-spectrum dominance" in all areas of warfare as part of creating the "new American century". Washington's neo-conservatives believe the US has an historic role to spread its free-market dream across the world. That way lie peace and security for the US and its allies, and stability and prosperity for like-minded people everywhere.
To the neo-conservatives it is obvious: communism is finished, capitalism rules and the US way of life is predominant. This doesn"t mean a neo-colonial role for the US, more a shaping of the world economy and polity in the US image. There is an implicit belief that no other approach is acceptable; any other vision is deeply wrong-headed, if not malign.
At the same time, there is a recognition that there are dangerous forces at work that do not recognise the wisdom and certainty of the neo-conservative vision. In a campaign speech nearly a year before his election and 18 months before 11 September, Bush said: "It was a dangerous world and we knew exactly who the -they- were. It was us versus them, and we knew exactly who them was. Today we"re not so sure who the -they- are, but we know they"re there."
Four years later, "they" are more easily characterised as international terrorists and "rogue states", with one of the greatest threats coming from rogue states armed with weapons of mass destruction - especially when they are carried on ballistic missiles.
An essential aspect of the neo-conservatives" vision of military dominance is missile defence. The programme would form part of a modernised nuclear arsenal that would have the ability to fight "small nuclear wars in far-off places". This arsenal would be complemented by a range of other weapons and forces including much-expanded counter-insurgency capabilities, long-range strike aircraft, massive blast bombs and, in the longer term, airborne and space-based lasers.
The missile defence programme is motivated by the concern that, in the fairly near future, some states may develop a limited deterrent capability that will curtail the US's freedom to act militarily in what it perceives as its interests. Much was learnt from the Scud missile problems of the 1991 Gulf War.
If missile defence can be made to work, then it removes the one limitation on US forces acting with impunity whenever and wherever necessary. The combination of such defensive systems with the world's most powerful offensive military forces (nuclear as well as conventional) will get remarkably close to full-spectrum dominance - helping to ensure that the new American century moves closer to reality.
Paul Rogers is professor of peace studies at Bradford University and writes a weekly column on international security for www.opendemocracy.comPaul Rogers is professor of peace studies at Bradford University and writes a weekly column on international security for www.opendemocracy.com