From left, a TV screen shows images of President Trump, South Korean President Moon Jae-in and North Korean leader Kim Jong Un on Wednesday at a railway station in Seoul. (Ahn Young-joon/AP)

Thursday’s surprise announcement about a face-to-face meeting between President Trump and North Korean leader Kim Jong Un followed news earlier in the week that seemed too good to be true: North Korea is willing to discuss denuclearization with the United States. The regime reportedly promised to refrain from conducting nuclear and missile tests during the talks and says it has no reason not to denuclearize as long as North Korea’s security is guaranteed.

Reactions ranged from cautious enthusiasm to dismay that Trump had accepted the invitation — rather than negotiate at lower levels and work toward a successful summit. The White House appeared to retreat from its snap decision a bit by announcing at Friday’s news briefing that North Korea would have to take “concrete and verifiable actions” before the meeting takes place.

Given the decades of failed attempts to resolve the North Korean nuclear problem, it may take a bold meeting like this to achieve progress. But three fundamental challenges lie ahead, leaving aside concerns about Trump’s unpredictable style — even in the most optimistic case that Pyongyang is serious about denuclearization:

Challenge 1: Credibility gaps

For North Korea to lay down its nuclear weapons, Kim must be genuinely convinced that the United States will not harm his regime. This won’t be easy, given Washington’s track record of taking out dictators, most recently in Iraq and Libya.

Strengthening the credibility of U.S. assurances will require extensive measures, such as a personal guarantee by Trump, a resolution from Congress, and/or a Chinese role in serving as a guarantor of any peace agreement. But even these measures, difficult as they will be to arrange, may not go far enough to satisfy a regime that is convinced the United States seeks to overturn it.

North Koreans will face their own struggle to prove their trustworthiness, given a track record of violating deal after deal they have signed in the past. Most observers believe North Korea will cheat and continue to expand its nuclear program in coming months. To prove he is serious about denuclearization, Kim would have to accept invasive International Atomic Energy Agency (IAEA) inspections in not only declared nuclear sites but also undeclared military sites as well. This is something most states, let alone a reclusive one like North Korea, would find hard to accept.

Challenge 2: Expectation gaps on the rules of engagement

For the U.S. side, the ideal scenario is that North Korea is willing to return to the breakthrough September 2005 Joint Statement of the six-party talks. This document commits Pyongyang to denuclearize in exchange for security and economic guarantees. But the agreement does not bar North Korea from engaging in other provocative actions, such as conventional military activities or cyberattacks. Any non-nuclear aggression by North Korea before, during or after talks could quickly lead to the breakdown of any progress.

North Korea, too, will most likely expect the United States to refrain from imposing additional sanctions or engaging in other punitive measures during negotiations. In fact, North Korea walked away from the six-party talks just after the September 2005 breakthrough when the U.S. Treasury imposed financial sanctions on a bank in Macau for laundering money for North Korea.

Washington’s position at the time was that the sanctions were justified and separate from the six-party process — but North Korea did not agree. On Tuesday, when news broke that North Korea was willing to talk, there were already signs of history repeating itself. The same day, the State Department announced new, albeit largely symbolic, sanctions on North Korea after formally determining it used chemical weapons last year to assassinate Kim Jong Un’s half brother, Kim Jong Nam.

To overcome these expectation gaps, the two sides could work out detailed rules of engagement to prevent the collapse of talks, although this would require extensive pre-negotiations. At the negotiating table, the United States could push for a comprehensive agreement that extends beyond just North Korea’s nuclear program to try to prevent the type of mutual disillusionment that has followed the Iran nuclear deal. But North Korea will most likely resist expanding the scope of the negotiations to the non-nuclear realm.

Challenge 3: Desired outcome gaps

Most importantly, talks could go nowhere if Washington and Pyongyang have wildly different end goals for the negotiations. While the United States may be willing to sign a peace agreement that says it will not harm the Kim regime and will normalize relations in exchange for North Korea’s denuclearization, Pyongyang may be seeking something altogether different.

For instance, Kim could ask for the termination of the U.S. alliance with South Korea alliance and the withdrawal of U.S. troops from the Korean Peninsula. This would probably be a nonstarter for both Washington and Seoul, regardless of whether Pyongyang were truly prepared to give up its nuclear weapons in exchange.

Given these daunting challenges, the chances that this opening, as unprecedented as it is, will lead to a final resolution of the North Korean nuclear crisis are slim. But now that the White House has accepted Kim’s invitation, meticulous planning of what can and cannot be put on the negotiating table, along with close coordination with allies, are in order. And perhaps an imaginative negotiation package, along with bold diplomacy by Trump and Kim, could pave the way to a more stable Korean Peninsula.

Patricia Kim is the Stanton Nuclear Security Fellow at the Council on Foreign Relations.