ROMA, Texas (AP) — The deployment of National Guard members to the U.S.-Mexico border at President Donald Trump's request was underway Tuesday with a gradual ramp-up of troops under orders to help curb illegal immigration.

The Trump administration also announced that Homeland Security Kirstjen Nielsen will visit this week a stretch of new border wall breaking ground in New Mexico, putting additional focus on what Trump has called a crisis of migrant crossings and crime.

The construction and commitment of at least 1,600 Guard members from Arizona, New Mexico and Texas provoked fresh condemnatio...