They are stalling. There is a lot of analysis out there that denuc can actually occur realistically speaking much more quickly, more quickly than the very slow pace they are purposely doing and trying to shift the discussion to Peace Treaty and US withdrawal from the peninsula first. Which is what they have always done. Its even got a name in Korean. Called the salami strategy
Well N.Korea said from day one they wanted a Official End to the War and US withdrawal from the peninsula. So why would it be any surprise they continue to ask for that?