Trump is sending 5,000 troops to Mexico border, but they can’t do much – Vox
The problem for Trump, though, is that the military won’t actually be able to participate in detaining or deporting any of the migrants the way the president likely wants. That’s because US law forbids them from physically detaining individuals at the border.
So while the troops at the border will be armed, they will only legally be able to assist US border officials by doing things like helping transport border agents and providing emergency medical care to those who need it. The armed forces can also work to reinforce infrastructure around the border, like putting additional razor wire on border fences.
In other words, while it may be intended to look as if the US is preparing for a massive invasion of immigrants at the Southern border, the reality is that it’s mostly just sending backup logistical support to help border agents address the arrival of a few thousand migrants — around half of whom are girls and women — who have been traveling by foot for weeks over.
via Trump is sending 5,000 troops to Mexico border, but they can’t do much – Vox
This stunt by Trump is partly to get right wing loyalists to the polls, and vote out of fear of this invasion by a bunch of desperate women and children being forced out of their countries due to violent US foreign intervention in South American countries.