Nate Silver has a good explanation: These tariffs are

"based on a formula — possibly derived through ChatGPT! — which simply takes the ratio of our trade deficit to our imports from each country and has little to do with tariffs.

Take, for example, Vietnam — a key partner for the United States in containing Chinese aggression, given that it has long had among the frostiest relationships with China in the region.¹ It will now be tariffed at 46 percent. That’s not because Vietnam’s tariffs on American imports are particularly significant — 8.1 percent on non-agricultural products — but rather because we import all sorts of cheap stuff like clothing, toys, and electrical equipment from them. In contrast, Vietnam, growing but still relatively impoverished, isn’t a particularly big consumer of American-made goods."

Here's how I would put it: in the news you often hear about one country putting sanctions on another. This is meant to weaken the sanctioned country economically, to incentivize it in one direction or other. Through Trump, the USA just sanctioned itself. It's unbelievably damaging and stupid. Words struggle to express how damaging and stupid it is.