President Trump prides himself on being a world-class negotiator. His candidacy, and now his presidency, have relied on that premise. He says he’ll “force the Iranians back to the bargaining table” on the nuclear deal; after scrapping the Trans-Pacific Partnership, he’ll secure bilateral trade deals with Pacific Rim countries and renegotiate NAFTA’s terms; Mexico, he insists, “will pay for the wall, believe me — 100 percent.” Never one to underpromise, last year he told one reporter: “Peace all over the world would be the best deal. And I think I would know how to do it better than anybody else.”

Trump the businessman has, indeed, haggled many business deals. He even wrote a best-selling book about it. Yet politician Trump is making mistakes that “Art of the Deal” Trump wouldn’t. He’s negotiating against himself — giving up leverage before there’s a corresponding ask — and he’s boxing in his negotiating partners, driving up the cost of reaching agreements, with potentially perilous results.

One explanation is that private-sector negotiations are quite different than exchanges in international affairs. Citizen Trump’s business negotiations have frequently been stand-alone deals: You build a tower, I’ll put my name on it, and we’ll share the profits.

Negotiating on behalf of the American people on matters of global security is far more intricate. On the world stage, deals are frequently multifacted, multilateral and for the highest stakes. Sometimes these are matters of life and death and war and peace. They cause reverberations and carry indirect and often unintended consequences across continents. I know, because I’ve worked on many of them. Negotiating with North Korea, the Taliban, Sudan and Cuba is not comparable to bartering with casino moguls, real estate czars and hotel chains.

When Trump signals that he’s considering moving the U.S. Embassy in Israel from Tel Aviv to Jerusalem, he needs to understand that this is not a simple, isolated act of support for Israel. It will significantly affect his existing dialogue, and any potential agreements, with Saudi Arabia, Egypt and other regional powers. Not because their governments are obsessed with the location of our embassy, but because it’s likely that many citizens in these countries will be marching in the streets in protest, and their governments’ credibility and stability will be on the line. The United States needs to stand firmly behind Israel; in my opinion, our recent abstention at the United Nations on a resolution condemning settlements was a mistake. But so far, Trump’s Bibi-can-do-no-wrong stance toward Prime Minister Benjamin Netanyahu has emboldened Israel to take the rare step of announcing a major settlement expansion. This will severely hamper future negotiations with the Palestinians to bring stability to the region.

These kinds of negotiations can’t be zero-sum. To reach successful, lasting international agreements, the president needs to serve the interests of the United States, while allowing his counterparts to claim their victories as well. If your counterpart can’t live with or survive politically the consequences of your deal, the deal won’t hold. As a diplomat, I always believed that in negotiations it was important to let my partners take credit and, when necessary, allow them to save face. In 1996, when I persuaded Sudanese rebel leader Kerubino Kwanyin Bol to release three Red Cross workers despite his initial multi-million dollar ransom demand, we held a joint news conference with several diplomats in attendance and praised Bol’s humanitarian gesture. We also promised him medical supplies for children in the rebel camp.

But by publicly stating over and over that he will make Mexico pay for his border wall and redo NAFTA, Trump makes it impossible for Mexico’s president to survive such a deal, even if, somehow, Trump managed to negotiate it out of him. He’s forcing President Enrique Peña Nieto to harden his own position. Tuesday, Peña Nieto’s government floated the idea of pulling out of NAFTA and lessening Mexico’s cooperation on cartels, security and immigration, all important U.S. interests. On Wednesday, Peña Nieto reiterated his opposition to the wall in a televised statement; Thursday, Trump threatened to cancel a planned meeting between the two leaders; a few hours later, Peña Nieto did cancel. They spoke Friday, but from here, the price of reaching a deal just goes up.

Unlike some business deals, international affairs and political agreements are rarely a one-time game. There is always a next round. Misbehave after you conclude a deal, and the next round will be more costly. Gloating about being a winner and calling your counterpart a loser will backfire bigly.

Negotiators should also keep as many options open as possible. “I never get too attached to one deal or one approach,” negotiator Trump writes in “The Art of the Deal.” “I keep a lot of balls in the air, because most deals fall out, no matter how promising they seem at first.” President Trump, however, seems intent on closing doors before he has an alternative lined up. He wasted no time signing an executive order that marked the United States’ withdrawal from the ­Trans-Pacific Partnership. Yes, it fulfilled a campaign pledge, but TPP was meant to give us economic leverage over China, and Trump just gave a lot of it away without lining up alternatives, thereby letting China back in the game.

In addition, by tearing up the TPP, Trump damaged our relations with 11 other important countries, including Australia, Canada, Mexico and Japan. The president’s claim that he will negotiate individual trade agreements with these nations is impractical and unrealistic. While he slogs along on 11 separate trade deals, the United States could be moving full steam ahead into trade wars with allies such as Canada and Mexico, as well as competitors such as China. Protectionism costs jobs and slows economic growth. We’ve lost the TPP and have, so far, gotten nothing in return.

Negotiator Trump argues: “The worst thing you can possibly do in a deal is seem desperate to make it. That makes the other guy smell blood, and then you’re dead. The best thing you can do is deal from strength, and leverage is the biggest strength you can have.” Committing to repealing the Affordable Care Act, before a new plan has been negotiated with the insurance industry and health-care providers, will make President Trump negotiate from a point of weakness, desperate to make a deal. Most negotiations take place out of the spotlight, and Trump’s comments about the ACA suggest that he has far less leverage in private. In 1995, Saddam Hussein agreed to release two American prisoners to me only after months of intense but quiet talks. All we had to give in return was a public thank you. Hussein never would have agreed to those terms had we been spouting insults and bluffs. Bombastic threats not only would’ve jeopardized the negotiations, they would’ve endangered those two Americans, workers for a U.S. aircraft company who had made a wrong turn in Kuwait.

Similarly, doing away with the Iran nuclear deal instead of using it as leverage to negotiate amendments and change the Iranian regime’s unacceptable behavior — such as its support for known terrorist organizations and calls for the destruction of Israel — would be counter to negotiator Trump’s logic. The deal is made. The Iranians have an interest in keeping it. In negotiator Trump’s words: “Leverage is having something the other guy wants. Or better yet, needs.” What does President Trump gain, negotiation-wise, by throwing his leverage away?

Finally, negotiators manage expectations. As Trump wrote: “I always go into the deal anticipating the worst. If you plan for the worst — if you can live with the worst — the good will always take care of itself.” President Trump, however, seems to have forgotten this principle, making sky-high promises that he may not be able to deliver on. And worse than in business deals, when the expectations you set in a political environment are higher than the results you achieve, you will be a disappointment and eventually lose support.

In an alternate universe, Trump the negotiator might very well proclaim Trump the president something of an amateur. “You can’t con people,” he notes, “at least not for long. You can create excitement, you can do wonderful promotion and get all kinds of press, and you can throw in a little hyperbole.

“But,” he adds, “if you don’t deliver the goods, people will eventually catch on.”