However improvisational his daily machinations on trade — presenting publicly as motivated by a random mix of mood and twitches of the news cycle, including the latest threat of tariffs against Mexico — Trump and his team are acting on a well-developed theory of the case, one that has been decades in the making.

In Trump’s case, that strategy is intuitive. He’s been saying since the 1980s — and by all evidence genuinely believes — that the United States is letting itself be played for the fool by foreign adversaries, on trade specifically and global competition generally. Strong nations robustly protect domestic industries and keep foreign competitors at heel. Back in the ’80s his focus was more typically Japan; in recent years, but long before 2016, he’s been focused on China.

In the case of his advisers, the theory of the case is more intellectual. They believe that the big bet free trade advocates made in the 1990s — that welcoming China into the WTO would encourage it to integrate into a rules-based global economy — has proved to be a loser. China, by these lights, is happy to take advantage of the U.S. and other players’ commitment to free trade and rules but will continue to steal and subsidize to advance its own interests.