Where's the plutonium?

Last night Bush said (about North Korea's nuclear program):

And by the way, the breach on the agreement was not through plutonium. The breach on the agreement is highly enriched uranium. That's what we caught him doing. That's where he was breaking the agreement.

It would appear that he's trying to correct someone's misstatement, presumably Kerry's. But, no one mentioned plutonium throughout the entire debate except for that quote. You can search the text here.

Perhaps he watched Nova this week and learned about the periodic table for the first time. I'd like to know what the fuck he was talking about. Seriously, if anyone knows please share.