After months of pretending to be normal and reasonable on the diplomatic stage, North Korea’s mask has slipped, and Pyongyang is back to threatening a “nuclear-to-nuclear showdown” that will “make the U.S. taste an appalling tragedy it has neither experienced nor even imagined up to now.”

Why is Kim Jong Un’s regime lashing out? It’s not because it is offended at talk of a “Libya model.” It’s because it was hoping to follow the “Iran model” — sanctions relief up front and weak inspections — and is starting to realize that is not going to happen.

When National Security Adviser John Bolton first raised the “Libya model,” he was not referring to the overthrow of Muammar Gaddafi; he was saying North Korea would have to carry out complete, verifiable and irreversible denuclearization (CVID) before the Trump administration lifted its “maximum pressure” campaign. That is what got the North upset. In a statement last week, North Korea rejected the “so-called Libya mode of nuclear abandonment, ‘complete, verifiable and irreversible denuclearization,’ ‘total decommissioning of nuclear weapons, missiles and biochemical weapons’ etc. … [and] ‘abandoning nuclear weapons first, compensating afterward.’” The Trump administration, the North Koreans said, “is trumpeting as if it would offer economic compensation and benefit in case we abandon nuke. But we have never had any expectation of U.S. support in carrying out our economic construction and will not at all make such a deal in future, too.”

In other words, Pyongyang rejected the very premise of Trump’s proposed deal: security and prosperity on par with South Korea in exchange for complete denuclearization. On Monday, Vice President Pence reiterated this is the only basis on which Trump would cut a deal. He pointed out that “the Clinton administration, even the Bush administration got played in the past. We offered concessions to the North Korean regime in exchange for promises to end their nuclear weapons program only to see them break those promises and abandon them.” He added that Kim will only end like Gaddafi if Kim “doesn’t make a deal.” Pyongyang in turn threatened the U.S. with nuclear annihilation if Trump did not come to the negotiating table.

Pence’s threat could not be what provoked Pyongyang’s fit of pique, since he was simply repeating with Trump himself had said a few days earlier when the president warned that Libya showed “what will take place if we don’t make a deal.” Rather, the North Koreans are angry because Trump is not budging from his demand, when what they want are front-loaded economic benefits in exchange for promises of “mutual” and “synchronous” arms reductions.

In other words, the idea that imprudent talk of a Libyan model somehow disrupted a potential deal is dead wrong. With its bellicose response, North Korea exposed the fact that it has no intention of giving up its nuclear weapons at the negotiating table.

This was further underscored by the PR stunt North Korea pulled this week when it unilaterally “destroyed” its Punggye-ri nuclear test site. This was portrayed as a sign of good faith, but as the Guardian newspaper recently reported, “North Korea’s main nuclear test site has partially collapsed under the stress of multiple explosions, possibly rendering it unsafe for further testing.” Because Pyongyang has no choice but to stop conducting nuclear tests at the site, they tried to take credit for doing what they had to do anyway. This is the kind of deceit Trump is up against.

The president made the right decision by calling off the summit, which should disabuse Pyongyang of the notion that he is desperate for a deal. Now, his conciliatory public letter to Kim Jong Un should be followed by tough back-channel warnings that the alternative to negotiations is not to continue the status quo. Sanctions will get tighter and military action is possible. My American Enterprise Institute colleague, Dan Blumenthal, suggests that Trump could also announce a major U.S.-Japanese joint project to develop missile defense capabilities to “shoot down missiles at their ‘boost phase’ (when they are at their warmest in their ascent and easier to track) through space, unmanned aerial vehicles, and other sensors and shooters” and also put major Chinese banks on notice that that they could face sanctions for financing of North Korean projects. “This would get the attention of both Beijing and Pyongyang.”

Trump should make clear to both North Korea and China, absent an agreement, that sanctions will get tighter and military action is possible. And that means the “Libya model” is indeed on the table.

© 2018, The Washington Post Writers Group