As you may recall, in February and March of last year, the Bush Administration made the case that Iraq was an imminent threat to the United States (although they may have not used those exact words), due to the fact that it would be able to directly threaten the United States with WMD.
What does this have to do with the Taepodong 2, North Korea's new ballistic missile? Everything. It was obvious that North Korea, with its clandestine nuclear weapons programs, and its geographic promixity to a large number of American troops stationed in South Korea, was much more of a threat than Saddam's Hussein's Iraq. However, North Korea does not have oil, and has the potential to inflict a horrendous amount of casualties on the civilian population of South Korea. As a result, preemption was ignored in favor of the more conventional policy of "engagement." However, not much is happening.
But back to the missile. FAS suggests that it would be able to hit targets in Alaska and western Hawaii. While such strikes, even if accompanied by a nuclear warhead, would most likely only cause minor strategic damage, a 1998 report by the "Commission to Assess the Ballistic Missile Threat to the United States" (headed by none other than our current Secretary of Defense) suggested that, "Light-weight variations of the TD-2 could fly as far as 10,000 km, placing at risk western U.S. territory in an arc extending northwest from Phoenix, Arizona, to Madison, Wisconsin."
As North Korea becomes more technically advanced without achieving social and economic reforms, it becomes more difficult for the United States to deal with it. Had we not become involved in Iraq, we would have both the administrative resources and the diplomatic capital to, at the very least, make a good faith attempt at resolving some of our differences with North Korea.