Much of the world was against Saddam Hussein, but it took the wholesale invention of an Iraqi nuclear program to justify and get authorization for deposing him through international military action. Iraq didn't attack us, though in attacking an oil partner they might as well have, but the public certainly didn't feel attacked until someone dreamed up the prospect of Iraq nuking Israel, Europe, and/or us.

In that case, the justification was a prerequisite to Congress authorizing a war without losing elections, and then selling it to the US's allies so we wouldn't have to send quite as many troops and thus lose elections. This administration demonstrably doesn't care about justification, authorization, alliances, or elections. So why bother? If they're going to stage an arbitrary Venezuela-like military operation in Mexico because of "cartels", they wouldn't wait for a civilian mass-death event, or for Congress, or regional allies, or public opinion. They didn't wait for any of that in Venezuela.

TBQH this just felt like a cheap and easy way for them to perpetuate the idea that we're always at war with terrorists. Now they're "narcoterrorists", but they're still "terrorists". And this administration might not like obstacles like authorization and due process, but it loves cheap, easy terrorists.