What did Donald Trump do today?

He tweeted out his belief that there is such a thing as "winning" a trade war.

After his abrupt decision yesterday to overrule his economic advisors and proclaim steel and aluminum tariffs, Trump immediately faced accusations that he was risking a trade war. Today, rather than argue that no such trade war would result, Trump actually came out in favor of trade wars as a concept, proclaiming them "easy to win."

This is, to put it mildly, a dangerous and stupid idea. There is no way to "win" a trade war. Every participant in a trade war, by definition, trades less than they otherwise would. Even if Trump's hoped-for trade war somehow managed to reduce the overall US trade deficit with the rest of the world, it would do so at the cost of the overall US economy.

Most tariffs are technical in nature and don't lead to retaliation, but then most tariffs aren't improvised on live TV. Overtly protectionist tariffs, on the other hand, tend to lead to trade wars. The Smoot-Hawley Tariff Act of 1930, one such package of tariffs, sparked retaliation from dozens of other countries. The resulting collapse of international trade didn't benefit the United States or any other nation, but it did make the Great Depression much worse. 

Why should I care about this?

• The United States economy is too important for a president to be this ignorant about how it works.