The postwar global economic order, with the United States at its centre, has created more prosperity than any other period in human history. Yet as Donald Trump takes a sledgehammer to that economic order, America’s democratic allies face a choice. We can accept the new cost of doing business with the US. We can follow the US down a path of mutually assured economic destruction with an ever-escalating trade war. Or we can find new avenues to keep free trade alive. My proposition? I believe we need a new platform for economic cooperation between the world’s seven leading democracies. Call...