The US has never had a policy of Preemption. Every war we have been in(with the exception of the Germans in WW2) has happened because American interest or forces have some under attack. Durning the 20th century war was justified most of the time by an attack, an ivasion, or support of a criminal. This military doctrine was fine in the 20th century because there was no threat that could reach the shores of the US with out our knowledge. We had no worry that an Army would cross the Atlantic or Paciffic with out our knowledge. The idea was that any war would start somewhere else and the Us would then send troops to repeal the attack, the American homeland would never be attacked. Infact only two wars have been fought on american land, the civil war and the revolutionary war. Because there is no imediate threat to the US, a policy of reaction is reasonable. However because of 9-11 the policy changed. Instead of worring about a nation state attacking US interest the US now had to deal with multinational terror organizations who's members had no nations flags. This presents a problem, the current policy of reaction dictates that we must let the terrorists attack first before we can react(i.e Afganistan). After 9-11 this policy became unaceptable. The american public would not allow an attack of the same magnitude on american soil again. Because of this the US adopted a policy of preemption. This policy allows the US to assert it's power over seas when it precieves a threat exists. This threat can be imideate or if left alone a gathering threat. Either way because of 9-11 the US can not sit back and wait for the US to be attacked. If a nation that is anti-US is invovled in any way with terror orginazations and this nation is thought to posses WMD's that nation is a threat to the US and under it's new policy can and should be attacked. Iraq fit that critera like a shoe. Saddam was anti-US and was hidding money and forces(look at the 10 bil he hid away) the UN until 9-11 was trying to remove the sanctions against Iraq which would have allowed it to openly pursue a weapons program and to openly, without policing, arm terror groups. In the terms of American security this type of risk can not go unchecked, or undetured. The US had the legal right to attack Iraq because of it's constant violation of the no-fly zone. It had openly shot at coalition aircraft since the 90's. With the threat precieved the US attacked and removed a wild card that if given time would have become a greater liability. This doctrine could also have been used against Lybia. Because as stated we knew Lybia was actively purssuing weapons and would have finished those programs soon. That is why with the capture of Saddam Lybia relized that it to could be changed at the end of an Abrhams tank. That is why Lybia captulated to the US and the UN and anounced it had pressued weapons and it wished ot abondon it's programs and open up to the US. It can be seen that allthough this policy is rather unpopular in the world at midly unpopular in the US this policy is nessicary in todays world. A threat can no longer be allowed to fester till it attacks. Because when it does it will not attack with planes and we wont lose 3,000. They will attack with WMD's and we will lose millions. Preemption is the only real deturence for Govt. who have any sympathy for terror. Like Bush said "you're either with us, or against us." That is a hard line policy, but with the invasion of Iraq our enimies know that we are serouice about this. if you are against us you're on a short list that has three members gone, two by force, one by surrender.