At the time, both of Ronald Reagan’s summits with Mikhail Gorbachev in 1985 and 1986 were failures. The agendas sprawled and the objectives—including, at one point, the virtual elimination of both superpowers’ nuclear arsenals—were lofty to the point of recklessness. Reagan walked away from a historic accord in Reykjavik to preserve the viability of space-based anti-ballistic missile technology, settling instead for a modest victory in the form of what Gorbachev called an “intellectual breakthrough” in bilateral relations.

Had Reagan succeeded on his terms, the deal struck between the two powers in Iceland would have badly strained American relations with its nuclear-armed European allies and provided an economic lifeline to Moscow that might have postponed the Soviet Union’s implosion. In retrospect, the president’s willingness to walk away from the table set the stage for one of the most astonishing events of the 20th Century: the peaceful end of the Cold War and the fall of European communism.

Thirty years later, Barack Obama would prove more flexible than his Republican predecessor. As early as his first months in office, the president communicated his desire to see a thaw in relations with the Islamic Republic of Iran. Arresting Iran’s progress toward a nuclear weapon was only one item on the agenda. Obama needed the aid of Iranian-backed Shiite militias in Iraq to fill the void left by the withdrawal of American troops from Iraq, and he was eager to appease the regime in Tehran to achieve that end.

The Obama administration frontloaded the deal with tens of billions in unfrozen Iranian assets, facilitated the revivification of Iran’s commercial ties to European and American firms, and agreed to the repatriation of suspected terrorists Obama’s own Justice Department had called risks to U.S. national security. Preserving the prospects for a deal led the White House to look the other way as Syria descended into chaos and convinced the Obamans of the need to appease Iran’s increasingly aggressive allies in Moscow. The deal did not allow international inspections at Iranian military sites, and even the International Atomic Energy Agency has indicated that Tehran is actively concealing potential violations of the terms of the agreement. If the Iran nuclear accords fail, it will be because it was flawed from the start; the product of an ideological conviction on the part of Barack Obama and his allies and not mutually beneficial terms hammered out over the course of a successful summit or two.

There are lessons here for American policymakers amid premature proclamations that peace has broken out on the Korean Peninsula. North Korea’s murderous and calculating dictator Kim Jong-un has crossed into South Korean territory where he and his South Korean counterpart negotiated a formal end to the Korean War. South Korea has agreed to dismantle its loudspeakers broadcasting propaganda across the DMZ. North Korea will verifiably close its nuclear test site and is purportedly willing to discuss “denuclearization” of the peninsula if the U.S. pledges not to invade the DPRK in exchange. All this is enough to make anyone giddy, and that’s the problem.

South Korean President Moon Jae-in is so committed to the idea of a peace settlement with Kim that he is already insisting Donald Trump should be the next recipient of the Nobel Peace Prize. At a campaign-style rally in Michigan over the weekend, Trump basked as his supporters chanted “Nobel” when the president talked up the ratcheting down of tensions on the Peninsula. If the verifiable denuclearization of North Korea was a result of a summit between Kim and Donald Trump, the president would surely merit that honor. Trump should not, however, fall in love with the vindictive prospect of humiliating his detractors by not only winning the prize but deserving it. That fantasy is the enemy of proper judgment, and it could lead this White House to abandon skepticism. And there is plenty of cause for skepticism.

The North Koreans have promised to dismantle a nuclear test site that already imploded last year, reportedly killing up to 200 people and rendering the site virtually inoperative. They have discussed the prospects of “denuclearization” of the peninsula, but without any specificity. In the past, Pyongyang has clarified that “denuclearization” means to them the total withdrawal of American forces from the Peninsula. The treaty negotiated by Moon and Kim is a political document. There can be no formal end to the war unless all the parties signatory to the 1953 armistice—including the United States and the People’s Republic of China—are participants. South Korea is willing to undermine the conditions that brought Kim to the table—a robust and uncompromising American sanctions regime buttressed by the credible threat of force—while Trump seems amenable to legitimizing a despot who tortures his people, murders his relatives, holds Americans hostage, and exports weapons, narcotics, and terrorism abroad. And for what? Aspirational pledges from a character with no credibility and a nation with a history of abrogating its agreements.

At present, the Iran nuclear deal is crumbling under the weight of its exposed pretenses and contradictions. Yet at the same time, Donald Trump is seemingly entertaining the prospect of another similar set of accords. Between meeting with Secretary of State Mike Pompeo, President Moon and, soon, President Donald Trump, Kim has received enough concessions from the West. It is time for him to demonstrate some confidence in the form of dismantling its offensive positions on the DMZ or allowing Western inspections of its nuclear facilities.

Trump should display that his commitment to a “good deal” or nothing at all isn’t just talk. The president should not let his fans fuel his ego and their own by fantasizing about the crow Trump’s detractors would have to eat in the event of a real peace deal. Nor should Trump allow himself to be the subject of transparent and elementary emotional manipulation by foreign leaders with their own agendas. That is how we get to a bad deal, and this might be the very last moment to avoid catastrophe.