Check out this piece, which describes how Kim Jong-Il is pressing for two-way talks with the United States:
North Korea said in comments published Wednesday that its self-imposed moratorium on testing long-range missiles from 1999 no longer applies because it's not in direct dialogue with Washington, suggesting it would hold off on any launch if the U.S. agreed to new talks.Now, this isn't necessarily true, but it's certainly an argument that the North Koreans could employ even as all involved understand the real reasons why the missile test was scheduled.
And those real reasons? First, the N.Koreans want to sell the thing abroad, and so it's a demonstration. More importantly, though, they also want the US to think that they're within a hairsbreadth of taking out Los Angeles, so as to goad the US into negotiating a firm "nukes-for-security" agreement that ensures that Kim Jong-Il doesn't suffer the same fate as Saddam Hussein. Since that's the entire point of their having nukes to begin with (who else would they be deterring? China?) there'd be little reason for them to keep the things afterwards.