Some of the National Guard troops that have been stationed along the U.S. Mexico border began training Thursday for various support roles.

According to reports, National Guard troops on the U.S. Mexico border have already assisted in the apprehension of 1,600 people attempting to enter the U.S. illegally over the last three and a half weeks.

The National Guard has been barred from having direct contact with illegal immigrants. Instead, guardsmen are training to be camera operators, radio dispatchers, and patrol lookouts. Some troops are expected to begin their new jobs as soon as Sunday.

According to ABC News, there are close to 1,600 National Guardsmen stationed along the border, although that number is likely to rise as U.S. Secretary of Defense James Mattis has approved for a max deployment of 4,000 Guardsmen if necessary.

The Department of Homeland Security is already asking the Pentagon for additional support along the border, including 700 more guardsmen, additional equipment, and even helicopters.

The Governors of California, New Mexico, Arizona, and Texas, have each sent a number of their National Guard troops to assist Customs and Border Protection. Those troops are expected to be stationed along the border until at least September 2018.