Britain’s new Prime Minister Boris Johnson will make his debut on the international stage this weekend, at the G7 summit of world leaders in Biarritz, France. There, Johnson will have his first chance as Prime Minister to win over – or alienate – presidents and other prime ministers who have the power to shape his time in office, and Britain’s future. President Trump, a self-declared friend of Johnson, is somebody who he will have to keep on-side during potentially divisive negotiations about a post-Brexit trade deal. And then there’s the European Union delegation, made up of Emmanuel Macron of France, Angela Merkel of Germany, and the outgoing top official Donald Tusk.