The latest verbal prodding came from President Trump during his joint press conference with South Korean president Moon Jae-in. Trump urged Pyongyang to "come to the negotiating table," and asserted that it "makes sense for North Korea to do the right thing." The "right thing" Trump and his predecessors have always maintained, is for North Korea to become nonnuclear.
It is unlikely that the DPRK will ever return to nuclear virginity. Pyongyang has multiple reasons for retaining its nukes. For a country with an economy roughly the size of Paraguay's, a bizarre political system that has no external appeal, and an increasingly antiquated conventional military force, a nuclear-weapons capability is the sole factor that provides prestige and a seat at the table of international affairs. There is one other crucial reason for the DPRK's truculence, though. North Korean leaders simply do not trust the United States to honor any agreement that might be reached.
Unfortunately, there are ample reasons for such distrust.
North Korean leaders have witnessed how the United States treats nonnuclear adversaries such as Serbiaand Iraq. But it was the U.S.-led intervention in Libya in 2011 that underscored to Pyongyang why achieving and retaining a nuclear-weapons capability might be the only reliable way to prevent a regime-change war directed against the DPRK.