The keyword in that political speech is "the cartels". My personal theory is that Trump and his political allies (MTG and Karri Lake, among others) have realizes they cannot longer use "the wall" as a vehicle to canalize the xenophobia into political power as Trump once did during his successful presidential run some years ago.
He did not accomplish his promise and it has wore off as strategy, so the solution is to go further, beyond the wall and talking about bombings inside México, without the approval of their southern neighbor.
In order for this speech to continue to be appealing enough he uses the drug crisis and the cartels as a new boogie man to rally his base, without raising (even more) serious debate in the ethical and legal problems of commiting those attacks on Mexican soil.

"Those are bad people we are attacking, bringing drugs and crime into our country". It is a pretty good moral cover, good enough for the misinformed.
Though, noone asks whether there are Americans citizens involved in the Fentanyl traffic, Trump implies there is none.

https://www.npr.org/2023/08/09/1191638114/fentanyl-smuggling-migrants-mexico-border-drugs