[vorpalhex]

...Yes. If you kill the people attacking the sensitive site, they will be unable to attack the sensitive site on account of being dead.

A thousand man force is a battalion. The cartels have no real armor and no air support. No heavy weapons. No training.

The US Army fields 31 brigades. A brigade is 5 battalions.

For every cartel member in your theoretical force, there are ~149 trained, armed, active duty service members in deployable condition for combat roles.

That doesn't include artillery, sustainment, the US Airforce or the US Navy. I am also not including guard teams which are another 27 brigades.

Your theoretical cartel force would also have to go through the Texas State Guard (1,700 people) and US Border Patrol.