Utah National Guard Sgt. David Cowley, attached to the 116th Construction Equipment Support Company, welds a wall along the U.S. border in San Luis, Ariz. The unit began work Monday along the border as part of Operation Jump Start.

San Luis, Ariz. ? Military bulldozers, road graders and other heavy equipment rumbled along the Mexican border early Monday as more than 50 National Guardsmen from Utah became the first unit to get to work under President Bush’s crackdown on illegal immigration.

The soldiers with the 116th Construction Support Equipment Company will hit their work sites by 5:30 a.m. during their two weeks of duty. They will improve a dirt road running parallel to the border, fill in gaps in fortified fencing and run wiring for new lighting to help the Border Patrol spot illegal crossers. The goal is to strengthen the border and free up border agents to catch illegal immigrants.

The Guardsmen are unarmed and wearing hardhats instead of Kevlar helmets. They will not perform any law enforcement duties. Most of the 11 soldiers assigned to operate the heavy equipment have full-time jobs in the construction business.

The troops arrived in Yuma on Saturday and were briefed Sunday on their mission and given tips on how to survive the heat of the Arizona desert.

Under Bush’s plan, up to 6,000 Guardsmen will be sent to the four southern border states. Officials say 300 Guardsmen from Arizona will deploy to the border in mid-June.