Transcript for Former UN Amb. on revived NK summit: 'Danger now is this will be a gigantic photo op'

Will be. He argues well since Singapore went very well it really gets you know you've kind of day. Situation. I never said it goes in one meeting I think it's going to be a browsers. But the relationships are building and that's a very. Got a casual press conference and that's an historic summit there the president on Friday asking that he will be going to Singapore on June 12 for them reading. With Kim Joan we want to talk about that summit now with our panel of experts including former UN ambassador Bill Richardson. This jump North Korea eight times has negotiated extensively with the regime there. Sumi Terry spent nearly a decade as a senior analyst concrete issues at the CIA before serving on the National Security Council under both presidents bush and Obama now a senior fellow. At the center for strategic and international studies. And our newest ABC news contributor Tom posture he was present trumps Homeland Security counterterrorism advisor. Senior policy and George W Bush's National Security Council welcome to ABC. News time great to have you here. And ambassador let me begin and with you as a city negotiate with the north Koreans on several occasions we've never seen a presidential summit before. Are the conditions ripe for this summit and how would you define success. Well I I believe. The danger now is that this'll be a gigantic. Photo op now I've supported the president would this summit in the past North Korean negotiations from the bottom up of not work. I'm glad this summit is reinstated. But you know the north Koreans are negotiator whether they maneuver you into a corner they never say no they're relentless they're focused and now our position. They shifted. Dramatically now we are saying. We are four and OK where the phase denuclearization. Still we should have the summit still we can get gains what is success. I think success is some kind of curbing of the use of nuclear and missile testing. Destruction of weapons. Missile and nuclear may be over a phased process. Number two I think. A reduction in the pension. With South Korea of the artillery the after all point five me and South Koreans are vulnerable American troops in Japan. And in South Korea. So a definition of success. Is something where there's dramatic time lines. And inspections. Of what the north installations are doing that that could any case and so. That is key if we don't have that I think the two agreements we had in the Clinton and bush administrations going to be this same. They won't succeed poll unfettered inspection. Tom the investor raises a couple the concerns right there are other former diplomats have to have decided this photo of the president. In the Oval Office with Kim Yung Choi on Friday that big smile on a Stacey C that was inappropriate too much of a concession. To meet in that public away with Kim Jung on saint also saying that. The president would no longer play maximum pressure to North Korea they say the president giving up too much or to get this week. Yes though you know that I understand investors worried that dangers of photo op but the real danger here is thirty or more nuclear weapons on the top of missiles can reach yet states I think. All the criticism of the president's means lose focus on the ends that we're trying to achieve self. With all due respect I don't believe that this is really a situation the president to lose and so I think he's doing the right thing. President Clinton tried a bilateral approach. President Bush trying to multilateral approach President Obama tried in direct engagement the so what president trump is doing is can it just right. Direct bilateral and he's looking for a start draw down so what are we gonna get out of this I think success is defined as a strategic political decision to disarm. And I guess that's going to be the question he can present trump this is distort the fact that he's going can he get more than Bill Clinton got in 1994 than George W. Bush that. In early in his term. It's very unclear I mean we still don't have an agreement like quarantine you graduation testing and on the definition of being accreditation. Is North Korea winning two teen you've got life as we need to find it which is complete damn it why don't you aren't alone anyway. I don't think David is to be the idealistic expectations I knew we still have to set it up as a goal. But there was a sense for study that was just released was sick Kepler scientist says. Verification process is going pick fifteen urus. Because North Korea bristled would not have we don't know when or the weapons are if they how many to have. We don't hit and got thousands of underground tunnels that they are hit and so verification process is complete viewing daily to put the chiefs of me tell realistic expectation. And grip president Thomas sort of walked away from Seville will hide by his self. And silly you're echoing what ambassador Richardson says that does seem to be the big goal here right you know is there any way you can get a realistic. Verification procedure narrative where you actually have inspectors looking at them with three. Yeah I think there's very important point to make hearsay hecklers made a lot of news and there's lot of respect he's an expert in this matter. Let me say he's a physicist who say the North Korean nuclear program he says it would take fifteen years visited I don't know if Graham multiple times inside and out of he's the only west there's been permitted access. Queries wrong though is the assumptions that two and his conclusion. As a result a year or two or three for freeze and things that are very easy to accomplish in the short term he's just inaccurate on. He's making assumptions that are a little bit different from my understanding what president terms courtesy. In other words what president trump is doing is hurrying and that's not to be criticized he's moving faster now because it's just a threat but because he's trying to attain. Where ascertain. The motive and intent of the leadership. If they don't have the intent to make a strategic decision and that means disarm as a first step trees but halt and disarm term of their nukes in their missiles. Then this is a big waste of time all definitions and all the big protracted negotiations that might come after but all be for naught. Any investor rich thing you spend a lot of time in the room with the north Koreans. What about the president personally is he heads into that meeting with Kim Jung what does he have to be aware of what has yet to be careful about how she conduct himself. Well first he has to be. Dramatically prepared. Kim Jung owner will be very prepared he knows has nuclear programs well. Secondly I think the president has stood. A point one person the point person secretary Pompeo who's done a good job he's met with Kim Jung won twice. He's kinda rescued this last summit where this meeting with the spy chief. And third. I think the president because he is charming negotiator. He should take Kim Joseph wanna side. Because when you negotiate with a north Koreans they never give any concessions. Across a table in the negotiating room. Take amount and formally find a way to build some trust with a guy. You know he can't be trusted but. This is why inspections and disclosure of their arsenal is key. But find some time when. One on one together to build trust. To find a way to have. A phased denuclearization. But one that has time lines. Disclosure of their arsenal and then lastly inspectors international atomic energy inspectors. American inspectors and then also focus on things that are important to the American people. Like the remains of our soldiers from the Korean War I brought seven back. Their families around the country that want to see closure. On so many of our troops and service been. Whose remains are there I think a lot that a combination of human rights and nuclear initiatives. But that should be done on a personal basis but I saw you and and the president should avoid hugs smiles photo option as much as she can't that's good reiterated that evening that a lot they ceemea say uniting your departed. To the idea of building a personal relationship that the president can't wing it. Though he can now we get he needs to be disciplined North Korea spent. They spend all their energy 100% of the focus on United States and you don't have the gut with just came she was part of the negotiation process from 1992. These guys have prepared a Dino what they're talking what they know what they want so we need to be prepared and let's see what happens. Time it does seem like Casey Pompeo is the presence guy here not jumble. Yeah I think that's correct and I think that that's strategic move the president initiated long before and so remember when you criticize us for speed. Know that the president came into office with this on his mind pretty highly. Maybe just the thought here. We've all given advice to president trump I think a little advice to Kim Jong-un in this case first he's not met president trivia answer he better prepare for that. And second and I think can a nuanced. But these demonstrations of blowing up tunnels whether they're they're complete or whether their facades just for show. It's really not helping matters even if they believe that to be a helpful gesture. It does make later confirmation of our inspectors in what was in those tunnels and all that much more difficult and sent to build trust. I think they should stop taking those unilateral actions at this point he is confused romantic moment actually thank you all very much.

This transcript has been automatically generated and may not be 100% accurate.