Kerry was exactly wrong on the bilateral north korean negotiations. North Korean govt media is gleefully cheering Kerry on, they know he's another Clintonesque democrate that can be easily pushed around on foreign policy.
go look at the transcript to that question, you'll see Bush caught Kerry in a deliberate deception
. The US was willing to play ball on the nuclear fuel issue, there are certain types of reactors that don't use the highly enriched fuel that can be used for nuclear weapons, north korea deliberately violated this and has no other reason to do this than make weapons.