President Trump’s proposed tariffs on steel and aluminum have the potential to radically rewrite global trading rules, in a way that free traders won’t like.

In the wake of Trump’s announcement that a 25 percent tariff would be imposed on all steel imports, along with a 10 percent tariff on aluminum, several WTO members have already signaled they are getting countermeasures ready, leading to fears of a “trade war” that leads to rising tariffs and a crimp on the global economy.