I'd call that an act of war and any country that enables it including Mexico should get what they deserve - bombing of strategic targets.
Oh wait, Mexico doesn't have any strategic targets unless we count all their drug compounds and the homes of the corrupt politicians who take MILLIONS from them (El-Chapo.)
BOMBS AWAY!
How drug compound were not mercilessly bombed (because they have devastated our country) is beyond me.
I guess the argument is you would have to bomb so many countries in the world.
But I’d say the one that BORDERS you stands out!