Iraq has chemical and biological weapons and is trying to get nuclear ones. It is, in some ways, more advanced than Iran in that regard, but lacks key components (which it might be able to buy on the black market). Iraq has only a few old missiles but has been trying to adapt aircraft into cruise missiles of mass destruction. What makes Iraq dangerous is Saddam Hussein. Not a professional politician, diplomat, or soldier, he does not behave in ways that could be called rational or logical. No rational foreign leader would want to risk being caught selling a weapon of mass destruction to a terrorist group, and no logical military commander would fire chemical or biological weapons at US troops knowing how the US could respond if it chose to. But Saddam is neither logical nor rational.--Stephen V Cole
Remember the Axis of Evil? Well, Iraq is simultaneously the weakest and the most dangerous of the three. North Korea has at least one nuclear bomb (according to the CIA) and is building a second; it could perhaps build one or two per year. It also has an extensive chemical weapons arsenal, and a huge bioweapons program. North Korea is the only country in the world to vaccinate its soldiers against Smallpox. North Korea has missiles able to hit Japan, Alaska, Hawaii, and (on a good day) the continental US (albeit with no accuracy in target selection). But the country is broke and starving and is having to make no end of deals to get food. Because it is desperate, North Korea will sell just about any kind of weapon for money. Iran is the world's leader in state support for terrorism. It has chemical weapons and probably biological ones, and has been trying as hard as it can to get a nuclear weapon. It has an extensive array of missiles and produces a full range of weapons. Iran has been supporting radical groups in Central Asia. But Iran is also the least likely to provoke a direct war with the US.