President Donald Trump continues to treat his administration as an international diplomacy wrecking crew. His latest target is the Iran nuclear deal. Even U.S. intelligence agencies affirm that Tehran has lived up to the accord, but the president apparently assumes that any agreement he did not negotiate is the worst in U.S., if not human (and perhaps intergalactic), history.

The presidential repudiation obviously affects relations with Iran and the rest of the Middle East. But the repercussions reach far further.

Indeed, ever-hawkish UN Ambassador Nikki Haley contended that “the whole reason we’re looking at the Iran agreement is because of North Korea.” The administration, she added, is sending “the perfect message to North Korea, which is, ‘We’re not gonna engage in a bad deal, and should we ever get into a deal, we’re gonna hold you accountable’.”

Unfortunately, the issue is not what message she wants to send, but what message the North Koreans are likely to receive. And that almost certainly is that no Washington administration can be trusted in any denuclearization deal.

First, the North has no negotiating partner in Washington. Secretary of State Rex Tillerson indicated his desire to pursue diplomacy. However, Pyongyang is aware that Secretary Tillerson speaks for no one other than himself, and certainly not for his president, let alone future administrations.

The differences between president and secretary already loom large. President Trump even warned his secretary of state via tweet not to waste effort and time on negotiations with the DPRK. Moreover, the secretary faces near continuous rumors of possible resignation and refused to deny that he called the president a “moron.” Why would the Kim regime treat seriously anything proposed or even said by Secretary Tillerson?

Even if the North Koreans improbably reached an agreement which the president found acceptable, they could not expect him to uphold his own agreement. Donald Trump abandons policy positions without a second thought. The president once said he’d be “honored” to meet Kim, before threatening to send the “armada” and “totally destroy” North Korea.

Assume the unlikely: President Trump approves an agreement forged by Secretary Tillerson and doesn’t switch course before leaving office. Then his successor follows the Iran deal precedent and announces that the U.S.-DPRK accord is flawed since it doesn’t cover a host of issues which North Korea refused to include in the pact originally.

Or the next president might simply attempt to take down the less well-armed Kim dynasty. Today Supreme Leader Kim appears to be in control, but the system might be more brittle than it looks. If Kim appeared vulnerable to Washington he could find American promises suddenly become inoperative.

After all, in 2003 Muammar Gadhafi agreed to give up his chemical weapons and abandon his missile and nuclear programs. President George W. Bush promised that Gadhafi’s “good faith will be returned.” European governments celebrated the Libyan dictator.

However, once opposition emerged as part of the Arab Spring his friends disappeared. The U.S. and European governments immediately took advantage of his weakness, bombing Gadhafi’s forces and arming and training the rebels. After Gadhafi’s gruesome death Secretary of State Hillary Clinton suffered a bout of uncontrollable giggling as she proclaimed: “we came, we saw, he died.”

The DPRK Foreign Ministry noted: “Libya’s nuclear dismantlement much touted by the U.S. in the past turned out to be a mode of aggression whereby the latter coaxed the former with such sweet words as ‘guarantee of security’ and ‘improvement of relations’ to disarm and then swallowed it up by force.” Pyongyang saw America’s policy plain.

After all this, why would any North Korean government, especially one focused on regime survival, believe that negotiations with Washington could solve its security concerns?

In international relations “messages” matter. It is especially important to send the right one when both sides are talking about nuclear war.

Instead of issuing more military threats which only reinforce Pyongyang’s case for developing nuclear weapons, the Trump administration should demonstrate that it is a trustworthy negotiating partner. Diplomacy still may fail — the North has shown no interest in yielding its nukes, and has its own reliability issues. But the DPRK isn’t going to accept Uncle Sam’s word on faith.