What did Donald Trump do today?

He named an ambassador to Panama, which normally wouldn't really be newsworthy.

Today, Trump announced he had picked Kevin Marino Cabrera to be the U.S. Ambassador to Panama. Cabrera is a county-level politician in Florida, and has no obvious credentials: he's never worked in diplomacy, he has no apparent cultural or family ties to Panama or Central America, and it's not even clear from what little public record there is of him that he speaks Spanish. Nevertheless, he wouldn't be the first ambassador made as a political appointment to a minor allied country with a thin résumé.

However, it's not clear how much longer Panama will be an allied country. Panama's government ignored the first few taunts, but now the president of Panama is responding directly, pointing out that Trump is simply lying when he claims that Chinese soldiers are controlling the canal. 

Hostile relations with Panama could affect American companies' ability to use the canal, however. One of the justifications for the U.S. invasion of Panama in 1989 was that its dictatorial "maximum leader" Manuel Noriega really was endangering trade through the canal. Precisely because there was evidence to support those charges, that invasion had virtually unanimous support from the international community, as well as a majority of Panamanian civilians.

An unprovoked attack on a stable, commercially accessible Canal Zone would instantly turn the canal into an impassable war zone and lead to massive international backlash against the United States—which is why Trump's threats are empty, whether he knows it or not.

Some of Trump's allies are claiming that his sudden fascination with buying or invading America's allies is a negotiating tactic—that he is pretending to be unstable or ignorant in order to force concessions. That would make more sense if there were anything Trump actually wanted from Panama in terms of the canal, but American ships are already sailing through as fast as they can—for now.

Why does this matter?

• Ambassadors implement their government's strategy for dealing with foreign countries, which is impossible if the head of that government doesn't have one.

• It's stupid to make threats that absolutely nobody thinks you can back up.