North Korea wants disarmament talks which are linked to a bilateral non-aggression pact with the US. The US refuses any such suggestion. They don't want any situation that would take away their self-proclaimed right to attack North Korea, nor do they want a gradual unification of North and South Korea like most of the Koreans do, as that would almost assuredly reduce tensions and encourage South Koreans to think twice about the need for US military bases in Korea.
Nope... the US government is happy with the status quo -- a sanctioned, isolated, nuclear-tipped North Korea with paranoid-schizophrenic leadership, thousands of its people routinely dying of malnutrition, and in desperate need of the kind of money that arms proliferation can provide.
It should be noted that Bush also doesn't live in California, Alaska, Hawaii, Japan, or South Korea, all of which are in range of North Korea's missiles.