There are rewards aplenty if Donald Trump and Kim Jong-un come to an agreement at the summit this week

It is a measure of how far Donald Trump has taken the United States that no sooner has he finished with alienating his closest allies at the G7 summit than he should warmly embrace one of America’s oldest and most dangerous foes. Whatever else, that is a turn-up for the books.

Thus Canada, which has mingled its blood with America’s in two world wars, and which has sent nothing more lethal in the direction of the United States than high-quality maple syrup, is threatened with a trade war. By contrast, North Korea – which until very recently was lobbing intercontinental ballistic missiles with dummy nuclear warheads in the general direction of Guam, Hawaii and California and sent Otto Warmbier back to the US in a comatose state – looks forward to a warm reception, having its economic sanctions eased and a wave of investment from America.

Canada may have some punitively high tariffs on dairy imports from its southern neighbour, but it has never vowed to wipe America from the face of the earth. Go figure, as Mr Trump might say.

Mystifying as all that is, what is encouraging about the Singapore summit is that it represents a seemingly serious attempt by Mr Trump and Mr Kim to make the world a safer place. Their motives may be less than noble, but the Trump-Kim encounter matters – and, to place things in some kind of perspective, it matters rather more than a routine G7 session.

For all the very different reservations the world might have about these two super-egos, the prospect for success, however uncertain, is an undisputed good thing. It is better, surely, than the tweets, insults, threats and counter threats that could all too easily have escalated into war a few months ago.

This summit has been relatively rushed and was in doubt for a time, with the result that the usual preparatory work by “sherpas” is incomplete. Given that there has been no high-level contact between the two parties for a quarter of a century, and none at all directly with the White House, that could be a source of concern. Much depends on the “chemistry” between two combustible personalities, a dicey prospect. Even so, the outline of an eventual deal – one that will still take time to progress, and with inevitable setbacks – is already clear.

For Mr Kim, the prizes are tantalising. First, he craves respect. The initial meeting with the president will quench some of that appetite. Further meetings – an assumption based on hope rather than experience – will serve to add to his prestige, culminating, if it is not too much to ask one day, in a solemn treaty ceremony in Washington, Pyongyang or Seoul.

Second, Mr Kim wants to secure his regime from external intervention. The reason the dictator has so maniacally developed nuclear weapons was rational: fear of an American-inspired attempt at regime change. Mr Kim watched what happened to Muammar Gaddafi, to Saddam Hussein and almost to Bashar al-Assad, and took the lesson that renouncing or otherwise losing weapons of mass destruction is a virtual invitation to America to invade.

Thus, if a way can be found to denuclearise the Korean peninsula that doesn’t not weaken the Kim dynasty’s grip on power, and which involves some form of American or multi-power guarantee of his personal tenure as supreme leader, then that too will be seen as a historic gain. President Trump has shown himself disinclined to follow George W Bush’s doctrine of exporting US values and democracy, and Mr Kim has noted the change in attitude, as well as tacit acceptance of his survival by some members of the Trump administration, such as Rex Tillerson (though bellicose remarks by the likes of John Bolton almost spooked the North Korean leader away from the negotiating table).

Still, Mr Kim will want to be sure that his sovereignty will last longer than Mr Trump’s time in the White House. He might be reassured by multilateral guarantees of North Korea’s integrity from China, Russia, South Korea and Japan, as well as the US.

Third, if only for the sake of self-preservation, Mr Kim might prefer it if he did not have to starve his own people to maintain his own position. Despite the regime’s efforts, North Koreans are gaining more and more glimpses of life in the prosperous south – illicit DVDs of South Korean soaps and K-pop have had a corrosive effect among some of the young. Mobile phone signals can be picked up on the borders with the south and China. Mr Kim is shrewd enough to realise his hermit kingdom is slowly becoming more porous and correspondingly difficult to manipulate and control.

Mr Trump’s allies also have a point when they argue that tough economic sanctions – crucially backed by China – have made Mr Kim nervous and more willing to cut a deal. Much of the credit, in truth, rests with Beijing for at last pushing its awkward ally towards reform and talks – but it was Mr Trump who took the initiative.

The idea of peace for economic aid is a powerful one, no matter its origins, and an abiding one that will persist beyond this summit. Pyongyang would relish an injection of investment from its rich neighbours, along with increased trade. Peering into the future, we might even see a mildly liberalised economy evolving – small scale markets and enterprises, and foreign joint ventures. China has shown how transformational economic change can coexist with one party rule, and would no doubt like Kim to follow their example and take the road away from its Stalinist orthodoxy. Perhaps Kim might one day be coaxed to change his ways.

For President Trump, the rewards would be more straightforward: a reduction in the burden of defending East Asia; the removal of a threat to American and allied lives; and, a more fanciful hope given recent developments, including in Jerusalem, a Nobel peace prize.

More than all those will be the opportunity to demonstrate to the whole world, including American voters in the midterms, that he can indeed live up to his reputation as “the dealmaker” on a wider stage than the Manhattan real estate market. This is one enterprise, and an extremely rare one, in which the world can wish that Mr Trump and Mr Kim, the odd couple of geopolitics, can somehow find a way to have a dialogue.