Since the 2018 summit, amidst the ups and downs or negotiations, it was made clear that the government in Pyongyang would be unwilling to make any serious steps towards denuclearisation without 'reciprocal actions' from the US administration. During the Pyongyang summit with Moon Jae-in in 2018 the DPRK made it clear that they would agree to a shutdown and dismantling of the Yongbyon nuclear research and development facility, seen as the core of the nuclear program, but only if the US took 'reciprocal action'. What remains a mystery to onlookers is what in particular Pyongyang is looking for before it makes any concessions to the United States.
Leaving this open-ended is a smart move by the DPRK since they have yet to make any firm statements, in public at least, on what they are looking for in negotiations and what they are willing to give up in exchange. The US has acknowledged in recent days that there has been little achieved since the summit in Singapore. This second meeting will need to produce something substantial to avoid being written off as a repeat of the rhetoric-laden summit in 2018 and that is equally important to Donald Trump who is heading into an election next year and needs a political 'win'. This has sparked concern that he could be willing to give too much away in exchange for very little. One of the requests from the US side would likely be a freeze on some aspect of the nuclear and/or missile production believed to still be underway. This would have to be twinned with some form of monitoring to ensure compliance which could be difficult given that we are unlikely to see a full declaration of all aspects of the nuclear and missile program; the DPRK considers this information vital to its national security and therefore is unlikely to divulge it. A major focus may be the Yongbyon nuclear site which is already well-known to the international community and believed to be the centre of the nuclear program. Dismantling this site would be considered a major win for the US but comes with some significant obstacles:
1) They've done it before. The DPRK demolished a cooling tower at the site in 2008, as part of ongoing negotiations, in front of international journalists. The fact is, nobody knows the true extent of the nuclear enrichment program and so Yongbyon may well be less important than expected or remain active beyond any 'dismantling' efforts as in 2009 when the site was believed to be reactivated.
2) Inspections are paramount to success. Inspections by the IAEA or other foreign groups involve a certain level of trust that the information they divulge will not be used against them in future. Trust was a major theme in the DPRK FM Ri Yong Ho's speech to the UN General Assembly last year and the level of trust that exists between Washington and Pyongyang will be what makes or breaks the talks.
So what do the DPRK want out of these talks? Number one on the list is likely to be sanctions relief. Without any sanctions being removed the DPRK will see no incentive to keep moving forward with the process. There are many, including members of the US intelligence community, who strongly believe that Pyongyang has no intention of actually getting rid of its nuclear program which it sees as the only defence against US and foreign aggression. This means that they will be seeking compromise whereby they can maintain a small nuclear arsenal; this possibility became more likely since US special envoy to the DPRK Stephen Biegun acknowledged that the two sides still do not have a clear picture of what 'denuclearisation' looks like. They may also seek a formal end to the Korean War which is something that was demanded by the DPRK in the months following the Singapore summit.
Until the summit there is no way of knowing what is and isn't on the negotiating table. One of the prevailing fears amongst lawmakers in Washington is that the President will surrender too much in the name of concessions as he did in Singapore by suddenly cancelling a planned military exercise between the US and South Korea. There are still numerous issues which Trump could make use of during his negotiations. The harsh sanctions, the US military presence on the peninsula and ongoing joint-exercises are all thorns in Pyongyang's side which could be used as bargaining chips during the summit. As to whether or not they will be used as such by the President remains to be seen.