Kim Jong Il is a rational actor. He responses to incentives and is willing to bargain when he thinks he can get a good deal. He is not illogical. Leaders such as Ayatollah Khomeini believe so fervently in their cause that they can behave irrationally. Khomeini was willing to inflict greater harm on himself than on Saddam, with no real chance of outlasting him. That's illogical. Dressing up an assassination attempt in the clothes of a peace talk is ingenious and disturbing, not irrational.
When the U.S. attempts to force and or persuade Kim Jong Il to do what we want, we must keep in mind that he very smart and very capable. He will want to persuade us that he is a little nuts, because then we are more likely to blink in the international game of chicken.