WITH the ink still drying on the Singapore declaration, President Donald Trump was asked why the North Koreans were any likelier to honour its terms than all the previous nuclear agreements they have flouted. The difference, he said, was himself. “I don’t think they’ve ever had the confidence, frankly, in a president that they have right now.” It was a reminder that the only unifying principle in Mr Trump’s maverick foreign policy is his relentless eye for personal advantage.

That is apparent in his North Korea policy more broadly. To use a real-estate analogy: when he was first briefed on the state of North Korea diplomacy by his predecessor, Mr Trump perhaps saw it less as an existential threat than a fixer upper—an opportunity for an easy win. Negotiations had long been frozen over America’s demand that Kim Jong Un’s regime should give up its nuclear arms and the regime’s refusal to do so. Yet there were two ways an America president could shake things up: by promising Kim Jong Un more normal relations, or threatening him with war. Most North Korea-watchers considered the first unconscionable and the second unrealistic. Mr Trump, unburdened by such niceties, tried them both, sometimes in the same breath.

Whatever the merits of the ensuing detente, the tactic has paid off handsomely for the president. It has enabled him to create a semblance of historic progress, which has driven his supporters wild with glee and bookmakers to slash their odds against him bagging the Nobel peace prize. And in case the deal comes to nothing, he says he has a contingency plan. He will simply “find some kind of an excuse” to absolve himself of blame. This was so predictable it is amazing Mr Trump retains such power to shock. Almost all his disruptive foreign-policy moves, the rows with allies, withdrawals from international agreements, tariffs and threats of worse on every front, can be viewed primarily as tactical ploys intended to push his self-image as a decisive leader, honour ill-considered campaign pledges or stoke the partisan, nationalist and xenophobic sentiment from which he draws strength. Yet this strategy is liable to produce diminishing returns.

For additional context, consider that Mr Trump’s haymakers at the world order and diplomatic convention have so far been easy to throw. Obliterating Barack Obama’s legacy, by withdrawing from the Trans-Pacific Partnership, the Paris climate accord and Iran deal, was a cinch. Each step was applauded by partisan Republicans, and the costs America will incur as a result are mostly remote and hard to quantify. Haranguing America’s allies for better trade and security terms, the main vehicle for Mr Trump’s claim to be pushing America First, has been no harder. Western leaders are reluctant to argue back, because of America’s heft and occasionally—as in his scorn for their paltry defence spending—because Mr Trump has a point. The stifling etiquette of diplomatic relations has magnified the dramatic effect of his grandstanding. Mr Trump was horribly rude to Justin Trudeau after the G7 gathering last week. Yet the common diplomatic view that the sky fell in because he refused to sign the shindig’s communiqué seems faintly ludicrous. By such means Mr Trump has been able to smash the maximum amount of crockery, for maximum political effect, at a modest or intangible cost. But he will now have fewer opportunities for low-cost bullying or audacious dealmaking available to him.

He has no more big Obama foreign achievements to unwind. The next wave of international entities in his sights—NAFTA, NATO and the United Nations—would be far more damaging to leave, politically and otherwise. Mr Trump’s decision to withdraw from the Iran nuclear deal and levy metals tariffs on Canada and the Europeans has already raised the cost of mistreating allies. It has forced them to take retaliatory action and probably made them less willing to provide support for future Trump dealmaking, especially with Iran, which his advisers would like to turn to next. That is in part because they know the president’s disregard for the Palestinians has made the “ultimate deal”—a settlement of their argument with Israel—extremely unlikely. On trade, Mr Trump faces even more steeply rising costs. He has so far convinced his supporters that protectionism can be profitable as well as emotionally satisfying. Yet the negative consequences of the tariffs on foreign cars and trade war with China he has threatened might make them think again. Mr Trump’s opportunities for easy America First wins, in short, appear to have been exhausted.

Crude yet calculating

There are three ways this could go. First, he could restrain himself—a prediction often made, and never borne out. Indeed there are fresh reasons to think Mr Trump is not about to become more conventional. All presidents become more active abroad as their troubles mount at home; and he, beset by legal peril, could use a foreign distraction more than most. Alternatively, he could double down and attack the international system more fiercely. That would be consistent with his record—except in one respect. Mr Trump has proved the prognosticators wrong because he understands his interests better than they do. His divisive behaviour is more popular than they imagined. By extension, it is not uncalculated: Mr Trump wants to promote himself, not mayhem. So if the rising costs of his confrontational foreign policy erode his support, he would probably moderate the policy.

That raises a third possibility. The president may maintain his antagonistic style, but follow through on fewer threats and promises. He may still threaten war, in trade and militarily, but he will not start one, because wars are expensive and end up unpopular. He will still float audacious deals, but he will settle for smaller-bore pacts—recognition of an Israeli land-claim, perhaps, or a stillborn deal with the Taliban—that he can spin as something bigger. On balance, this seems likeliest. It is how he conducted his business. It also best describes the stunt he pulled in Singapore.