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.

The Trump administration’s attack on the Iran agreement is important evidence of Uncle Sam’s faithlessness. But this episode is neither the only nor even the most important reason for Kim Jong-un to refuse to trade his missiles and nukes for promises. The U.S. government has repeatedly demonstrated that Kim should not take its commitments seriously.

First, the North has no negotiating partner in Washington. Secretary of State Rex Tillerson indicated his desire to pursue diplomacy; he argued that the lesson of the Iran repudiation for the North is that “the United States will expect a very demanding agreement.” 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. The two disagree over NATO, the Saudi/UAE-Qatar dispute, the Iran deal, and talking with the Democratic People’s Republic of Korea, among other issues. President Trump even warned his secretary of state via tweet not to waste effort and time on negotiations with the DPRK. Moreover, the secretary’s tenure could be short. He 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?

Ambassador Haley appears to better represent the president’s blustery, threatening, and thoughtless approach. She is yet another former Republican governor who grew enamored of war after stepping onto the national stage. It is difficult to imagine her negotiating with Pyongyang. What kind of agreement she would find acceptable other than “I surrender”? That would be a nice result, but isn’t a likely outcome of any negotiations with North Korea’s Supreme Leader Kim.

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. He sharply criticized Asian, European, and Middle Eastern allies, before embracing them all, even Saudi Arabia, which he had accused of funding terrorism. He went from advocating evenhandedness for Palestinians to embracing Israel’s extremist Likud government.

The president once said he’d be “honored” to meet Kim, before threatening to send the “armada” and “totally destroy” North Korea. It doesn’t much matter what he thinks about the DPRK today. Next week he could hold an entirely different opinion.

Assume the unlikely: President Trump approves an agreement forged by Secretary Tillerson and doesn’t switch course before leaving office. Then his successor—say President Haley following a Neoconservative “Machtuebernahme” within the GOP—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. At which point she demands a series of concessions for Washington to live up to its commitments. After all, Pyongyang’s failure to downsize its conventional military, dismantle its political system, hand over Kim for trial, and agree to be “swallowed” by South Korea all violate the “spirit” of the agreement, as interpreted by Washington.

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 Ghadaffy agreed to give up his chemical weapons and abandon his missile and nuclear programs. President George W. Bush promised that Ghadaffy’s “good faith will be returned.” European governments celebrated the Libyan dictator. Even America’s infamous militaristic triumvirate of Senators John McCain, Lindsey Graham, and Joseph Lieberman enjoyed a friendly dinner in Tripoli with Ghadaffy at which they discussed providing U.S. aid to reward him for assisting against al-Qaeda.

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 Ghadaffy’s forces and arming and training the rebels. McCain, Graham, and Lieberman resumed their unending war dance. After Ghadaffy’s gruesome death, Secretary of State Hillary Clinton suffered a bout of uncontrollable giggling as she proclaimed: “We came, we saw, he died.”

The North Koreans are many things, but they are not stupid. 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? Who believes Kim & Co. to be utter fools?

In international relations “messages” matter. In sending hers Ambassador Haley may believe that she’s still in Columbia, South Carolina, dealing with small town legislators over the next road bond issue. Maybe as governor she found them easy to swindle, with little political consequence. Unfortunately, similarly tricking North Korea won’t be as easy.

It is especially important to send the right signals 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 major reliability issues. But the DPRK isn’t going to accept Uncle Sam’s word on faith.