In the U.S. fight against illegal immigration, the focus is shifting to Mexicans breaching the southern border. 

Policies imposed by the Trump administration last year successfully prevented crossings by other Central American migrants. 

But Mexicans aren't covered by the so-called "Remain in Mexico" program. 

So, as CGTN's Alasdair Baverstock reports – the U.S. is employing another tactic.