When Donald Trump was first elected in 2016, I remember going around Washington, asking various experts what they thought he might do on their patch. They all offered pretty much the same answer: they had no idea. Australia’s prime minister did not even know how to get in contact with Mr Trump to congratulate him on his unexpected victory—until some bright spark in the DC embassy asked Greg Norman, a champion Aussie golfer, who (of course!) had his mobile number. 

Nine years later, the unpredictability of America’s president is the single most flummoxing thing in world affairs. On August 15th Mr Trump is due to sit down with Vladimir Putin in Alaska to discuss the future of Ukraine. No one knows whether he will stand firm and secure a ceasefire that might last, or be in such a hurry to normalise relations with Russia that he caves in to Mr Putin’s outrageous demands. 

In this week’s Europe section we report on the flurry of proposals circulating in advance of the summit, some of them truly alarming. (Mr Putin wants Ukraine to surrender land in exchange for empty words.) But since our deadline falls before the summit begins, we cannot know the outcome. So our cover leader steps back and considers the global consequences of Mr Trump’s uniquely personal and capricious approach to foreign policy. It looks at how his dealmaking works when the stakes are low (sometimes well) and when they are high (usually badly). Also in this week’s issue, our Lexington columnist analyses Mr Trump’s unusual relationship with the world’s most dangerous despot.