The real terrorists do not have the ballistic missiles
Simple logic lies behind US President George W. Bush's missile defence strategy - Americans want protection.
There is nothing new about such an idea - it has been used by Republicans and Democrats as a vote-puller for five decades. Republicans, though, are most closely associated with the concept, which has become a pillar of their ideology.
Politicians are in a bind. With terrorism on American soil the biggest perceived threat, they have little choice but to follow their political instincts. Republicans want a missile defence so that they can be labelled 'pro-defence', while Democrats, even though they do not want such a system, back it because they fear being called 'anti-defence'.
As a presidential candidate in May 2000, Mr Bush said it was time 'to leave the Cold War behind and defend against the new threats of the 21st century'.
A year later and in the White House, he outlined his missile defence plans. The 1972 Anti-Ballistic Missile Treaty has since been scrapped.
Since the start of the missile age during World War II, when German V2s spawned fear in London, US administrations have been searching for better ways to defend their country.
The Cold War sparked the arms race and weapons proliferation, but the collapse of the Soviet Union has not meant a change of attitude. Rather, it has meant an upsurge in fear of rogue states.
Experts argue that there is little logic in such an idealistic approach. They say Mr Bush's missile defence shield is no protection against Russia's 700 inter-continental ballistic missiles or the 20 China already has and is improving through large military spending increases.
North Korea is believed to be developing long-range missiles, but the accuracy of its short-range versions are questionable, so the threat is seen as minimal.
Anyway, the Cold War is over, so what is the threat? Researcher Victoria Samson of the Centre for Defence Information, a Washington think-tank, said Defence Secretary Donald Rumsfeld's assurances that there was nothing symbolic about missile defence were not convincing.
'You have to wonder what has changed that you need to have something in place by 2004,' she said.
'More cynical people can say there's going to be a presidential election that year and the administration wants to be able to say 'Yes, we've put something in place, we're providing a missile defence'.'
Ms Samson said the system was even more questionable because it was still being developed. Even though an annual US$8 billion (HK$62.4 billion) had been set aside, the final cost was unclear, with estimates of between US$100 billion and US$500 billion.
Those points seem lost on taxpayers and politicians, who are missing the most obvious piece of logic in making their arguments.
The biggest threat to the US is not missiles roaring over the Pacific, but something rather less easy to detect - a nuclear-weapons-laden suitcase.