>> North Korea says it's willing to discuss ending its nuclear program. But experts warn the regime may be just buying time to build up its arsenal during any talks with Washington. President Donald Trump says Pyongyang's offer seems sincere.>> I really believe they are sincere. I hope they're sincere, we're gonna soon find out.
>> But as his advisors huddle with South Korean officials who met with Kim Jong-un this week, skepticism is running high. Matt Spetalnick is covering the story.>> The North Koreans have told the South Koreans while talks were underway they would be willing to freeze their nuclear and missile testing.
What they have said they're not willing to do at this stage is to entirely freeze their nuclear programs. That would leave the North Koreans with a number of options for work that could be conducted on the ground to beef up their nuclear arsenal and refine their missiles.>> That could include completing development of a reentry vehicle that could deliver a nuclear weapon to the United States.
Negotiations could give Kim time to produce rocket frames, engines, and mobile launchers or to boost his output of plutonium and uranium, adding to his nuclear stockpile. Officials say any diplomatic discussions are a step up from the insults and threats of war that have marked relations between Trump and Kim so far.
>> US officials are especially wary, because North Korea has a long history of reneging on its international commitments over its nuclear program. So they say they will be watching closely to see if North Korea attempts to drag out the talks in order to move ahead in other areas of their programs.
>> Veteran negotiators say Trump should be ready to pull the plug if it becomes clear that Pyongyang is just trying to stall for time.