Certain groups in the US have been building up to this for a while. They genuinely do want a war with Mexico. They've been trying to use drugs as an excuse to do it.

Here is an excellent video going into this when it all started to get quite serious and AMLO (mexican president) started to aggressively fight back against it: https://youtu.be/3dw1pcDoewY

He's also called the american media sphere trying to build up to this fascistic "hitlerismo", comparing american media to goebbels.