Especially because I don't think the President even has to power to levy these tariffs.

His main arbitrary tariff power is to address "unreasonable" or "unjustified" acts by other nations, but only when that act "burdens or restricts" commerce. Colombia not taking their criminals back doesn't really affect U.S. commerce.

They're probably thinking if he goes to Congress and gets a real tariff it'll be really hard to reverse and they'll be screwed. I bet Mexico's cartel-President Sheinbaum will call this bluff and then she'll find out.