Active duty military troops will begin arriving in El Paso, Texas, and San Diego on Thursday evening, in what defense officials said is the first batch of the new forces being deployed to secure the southern border.

The year ended with the lowest number of migrant encounters along the U.S.-Mexico border in a long time, with San Diego no longer the busiest crossing route in December as traffic spiked in Texas, according to the latest data from U.

The Pentagon said Wednesday it has begun deploying 1,500 active duty troops to help secure the southern border, putting in motion plans President Donald Trump laid out in executive orders shortly after he took office to crack down on immigration.