He wants to send 4000 National Guard members to be precise. Both Texas and Arizona have already deployed members, while New Mexico and California are being called to do the same. All this is after the lack of information on the construction of a border wall, one of Trump’s key campaign promises.
The additional personnel is supposed to help stop the practice of “catch and release”, where illegal immigrants are taken in but freed before it is decided whether they should be detained. This means that a lot of them disappear into society and it becomes harder to find them.
However, sending the National Guard to strengthen the border is not new, during their terms both Obama and George W Bush sent personnel as well. Though for many crossing the border, these policies do not matter to them, they just want a better life for themselves and their family.