Supporters of President-elect Adama Barrow lay a Gambian flag across a poster of incumbent President Yahya Jammeh.

Donald Trump has made too many promises to ever be able to keep them all. The trick is to figure out which ones he will keep and which he won’t. To help us think through the Trump era, here are five categories of promises recently reversed by world leaders.

5. Game theory. OPEC surprised markets in November by agreeing to cut the production of oil after years of having failed to reach a deal. Consensus was hard in part because Persian Gulf officials had said they couldn’t reach one without Iran cutting production. Now the group, which includes the Saudis, is giving Iran a pass. That promise aside, there is plenty of reason to be skeptical of the deal. For one, keeping supply down and therefore prices up relies on non-OPEC members like Russia going along. But historically, as a former Saudi oil minister was quoted saying, “we tend to cheat” (“we” being OPEC members). OPEC itself has no enforcement mechanism, and knowing all other members can’t be stopped from cheating gives each of them an incentive to overproduce. Possibly the most famous attempt to make OPEC stick to the program was in 1990, when Iraq moved its forces to the border of Kuwait in an effort to reduce that country’s overproduction. Kuwait cut production, but Iraq invaded anyway. Perhaps a little cheating on your promises isn’t so bad.

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4. Falling on the sword. In the run-up to June’s Brexit referendum in the U.K., then-Prime Minister David Cameron repeatedly promised that if the U.K. voted to leave the European Union, he would trigger the irreversible legal process known as Article 50. Six months later, the U.K. still hasn’t pushed the official exit button, though Theresa May has promised it will come early next year. In the immediate aftermath of the vote—just before invoking his own personal Article 50 and exiting the prime ministership—Cameron insisted the country needed time to figure out what relationship it wanted with the EU. In other words, lacking a plan if the vote went against him, he took the self-sacrificial decision to give his successor some breathing room.

3. Base play. Last year, after months of difficult negotiations with Greece’s creditors, Prime Minister Alexis Tsipras urged his supporters to reject a bailout package that he called “blackmail.” Greeks followed his lead, voting no in a referendum he called on international negotiators’ proposal. And then Tsipras went and agreed to the austerity package anyway, avoiding almost certain financial ruin for the country. The most charitable interpretation of Tspiras’s behavior is that, before the referendum, he was caught in an untenable position between the demands of international negotiators and promises he had made to his base, and decided to try to prioritize his base. After the referendum, he could at least say to them that he had fought and lost.

2. New consequences. Two weeks ago, Gambian President Yahya Jammeh stunned observers when he conceded to his opponent in the country’s presidential elections. For someone who has promised to rule for a billion years, his decision to walk away peacefully was a remarkably positive turn for the country. And then Jammeh reversed course again, saying the election results had been discredited. His exact reasoning is murky, but one credible suggestion is that the country’s newly elected leaders had started talking about prosecuting him. Nothing clarifies the mind like the idea of a prison cell.

1. Overcommitment. In August 2012, Barack Obama walked into the White House press room and told reporters that the use of chemical weapons by Syria’s Assad regime would constitute a red line that, if crossed, would prompt U.S. action. Three years later, as eastern Aleppo falls into Syrian government hands, it has never been more clear that Obama made a promise he was not going to keep. As he told Jeffrey Goldberg, the president thought following through would be falling into a trap. He had, in other words, committed to something he didn’t believe in and simply had to walk away, having judged the consequences worth suffering.

This article has been adapted from Matt Peterson’s weekly newsletter for Eurasia Group, Signal.