PRESIDENT Donald Trump was always contemptuous of the Obama nuclear deal with Iran. The Iranian negotiators ran rings around John Kerry, Obama’s dull secretary of state. The Europeans, eager to profit from lifting sanctions, nodded through an agreement that in fact did little to stop Tehran’s nuclear plans. Even more outrageously, in his eagerness for at least one foreign policy triumph in his two-term presidency, Obama threw aside support for his allies and did not seek to halt Iran’s violent and devastating interference in the Arab World.

Donald Trump’s rambling and repetitive “Art of the Deal” may not be one of the greatest business books ever written but it certainly makes clear the ruthlessness that characterized the president’s corporate career. He maintained a key factor in success was to know the bottom line, to recognize the minimum acceptable to require his signature. On the way there, he would flatter and praise but beneath the generous words, he insisted he always knew where to draw the line. When the negotiations were going the wrong way, he played hard ball. He was always prepared to gather up his papers and walk away from the table.

Washington is focused on another nuclear deal, this time with North Korea. Donald Trump’s White House has got further in talks with Pyongyang than any previous US administration. This is because the president was prepared to take the risk of meeting Kim Jong-un, whom he once called the “Little Rocket Man”. The first encounter in Singapore last June looked promising. The second meeting in Vietnam this year was rated by most of America’s liberal media, with its vitriolic hatred of the president, as a humiliating failure. It was probably no such thing. Trump walked out when Kim tried to remove some of the negotiating headers to which he had formerly agreed. In leaving, Trump made clear he was well aware of the past North Korean tactics of “one-step forward, two steps back” that had so befuddled previous attempted US talks. He was not going to put up with them. But he kept the talks going led by Secretary of State Mike Pompeo.

Now Kim is seeking to turn on his own pressure. This week, he oversaw in person a new missile test. He also described Pompeo as “talking nonsense” and being “reckless” and insisted Trump remove him from the talks, before they resume. Pyongyang has been suggesting to diplomats a meeting between Kim and Russian President Vladimir Putin is currently being discussed. Given Kim’s horror of air travel, it would be an even longer train journey to Moscow than he took this year to Beijing. And moreover his luxurious state train could not travel on the wider gauge Russian tracks.

In Singapore, Kim pledged to stop nuclear and intercontinental missile tests. Though satellite intelligence suggests nuclear work is continuing, this week’s launch was not of an intercontinental rocket. Unlike the Iranians, who have used North Korean technology, Kim appears to be mostly sticking to the deal. But with reports of fresh food shortages, he needs to tell his dragooned and pauperized citizens the same old story, that they are still threatened but being well defended. However, can he really afford to have Trump walk away, which if he has bothered to read the book, he must know the president will do?