Prime Minister Turnbull and President Trump have agreed that Australia will be exempt from America’s new section 232 tariffs on steel and aluminum on national security grounds. That’s a relatively cheap concession for the U.S. given Australia only accounted for $424 million of America’s imports of the metals covered in 2017, or 0.9% of the total. That may indicate that heads-of-state level engagement may be more fruitful for delivering exemptions than those at the trade minister level. The EU and Japan have attempted – and appear to have failed at so far – at using the latter route. Y...