That is not really how things have proceeded with the United States and North Korea. Mr. Trump has already committed to granting North Korea one of its most desired concessions: a high-level meeting between the heads of state.

In exchange, North Korea has not publicly committed to anything. It has, quite cannily, channeled its public communications through South Korea, making it easier to renege.

Further, Mr. Trump has declared “denuclearization” as his minimal acceptable outcome for talks, making it harder for him to accept a more modest (but more achievable!) outcome and costlier for him to walk away.

The table is now set in such a way that virtually any outcome is a win for North Korea, but only a very narrow and difficult range of outcomes will save the United States from an embarrassing failure.

The North Koreans can walk away more freely, while the Americans will be more desperate to come home with some sort of win. It’s a formulation that puts the Americans at significant disadvantage before talks even begin.