What did Donald Trump do today?

He made empty threats at yet another friendly country.

In recent weeks, Trump has made threats—apparently serious in his own mind, at least, to invade Mexico and annex Canada. To put it mildly, these threats have not been taken seriously by their targets. Today, for whatever reason, he threatened to seize the Panama Canal because it was charging American ships to pass through it—which is what all canals do.

The canal was originally administered by the United States. The Canal Zone, a ten-mile-wide strip of territory that cut the nation of Panama in half, was ceded back in 1979 as part of a treaty process. This was relatively uncontroversial at the time, bipartisan in terms of American politics, and was seen as benefiting both nations. Anger over the Panama Canal Treaty quickly faded to the fringes of American politics.

(Trump was accused of evading Panamanian taxes in 2019, but that complaint came from the business partners who say he ripped them off, not the government of Panama itself.)

Of course, there's nothing stopping Trump from invading a sovereign nation and seizing its canals, except what stops the United States from trying to conduct wars of aggression against any country's territory that might be useful to have: the strong likelihood that it would polarize the rest of the world against us, strengthen our actual enemies, and do far more economic damage than not invading.

Why does this matter?

• Making threats that nobody takes seriously only makes the country weaker.

• It's a problem that we can't tell why Trump is suddenly extremely agitated about an issue that hasn't been in the headlines since he was in his mid-30s.