IIRC he tried the same thing during the Afghanistan fiasco
CBP/Border Patrol were in Afghanistan and Iraq for years training their immigration/customs and border counterparts.
Several were killed by their "students". The Border Patrol is kind of like the US Army Special forces. Training indigenous LEOs.
This is nothing new they have been in Central and South America for years. I would estimate that no more than 45 are out of the country at any given time.