What did Donald Trump Do Today?

He reacted to the news that Fidel Castro had died with a four-word tweet: "Fidel Castro is dead!"

How is this a bad thing?

• It's bad if the president-elect doesn't know about diplomacy.

• It's bad if the president-elect knows but doesn't care about diplomacy.

• It's very bad if the president-elect knows and cares about diplomacy but can't restrain himself from undiplomatic pre-dawn tweets anyway.