Factories holding hundreds of centrifuges spin gaseous uranium until it is enriched in a rare form of the element that can fuel reactors — or, with more enrichment, nuclear arms.

It’s easy to shut down such plants and dismantle them. The problem is that they’re relatively simple to hide underground. North Korea has shown off one such plant, at Yongbyon, but intelligence agencies say there must be others. The 2014 Rand report put the number of enrichment plants at five.

Because uranium can be used to fuel reactors that make electricity, North Korea is almost certain to argue it needs to keep some enrichment plants open for peaceful purposes. That poses a dilemma for the Trump administration.

In the case of Iran, it has insisted that all such plants be shut down permanently. After arguing that the Obama administration made a “terrible deal” by allowing modest enrichment to continue in Iran, it is hard to imagine how Mr. Trump could insist on less than a total shutdown in North Korea.