Saddam took a chunk of our oil supply (Kuwait) back in the day, and threatened another (Saudi Arabia). We had two choices then:
A) Send him a ‘Congratulations on your victory!’ card, and an order for however many barrels of crude. Light and sweet, please, hold the fuel oil.
or
B) Liberate Kuwait, and eliminate the threat to Saudi Arabia.
We chose plan B, which set of a series of events, most important among them being that we now had a seriously pissed-off Saddam still in power, looking to develop more effective WMD.
Part of the cease-fire agreement we made with him contained provisions that he would eliminate all actual WMD, delivery means, and production means, and for the verification of the same.
He has not lived up to his part of the cease-fire agreements, which means he is still a threat to a large chunk of our oil supplies.
He no longer posses any credible threat through conventional armed forces; Like most dictators, he values percieved loyalty over effectiveness in his armed forces, and it showed, and still shows. The lone partial brigade we keep in Kuwait is more then plenty to deter any future conventional attack.
But WMD change the game considerably, maybe. Nobody really knows for sure, since modern WMD have rarely been used in modern conflict. VX could cause massive casualites among our forces. Or it could be detected and countered with those goofy autosyringe thingees. Who knows, and I won’t even touch on the potential of Iraq covertly supplying even small quantities to terrorists.
Still, to be on the safe side, he is forbidden from having them. According to some sources, he has them. According to others, he does not. He is not being forthcoming, so buh-bye.
North Korea, on the other hand, can be starved into submission, even though that carries some dangers. Still, we have options in dealing with N.Korea; Our options in Iraq have been exhausted over the past 12 years.