At a time when the National Guard has been doing extended tours abroad, President Bush has added a mission at home.
The first National Guard unit has just arrived on the Mexican border for its first mission: building corrugated metal fences topped with barbed wire in San Luis, Ariz.
"I'm grateful for the opportunity to, to protect our nation," said Benjamin Grimstead, a member of the Utah National Guard.
President Bush will make his second visit to the Southern border today, in less than a month. He is expected to visit a Border Patrol training center in New Mexico and a sector headquarters in Texas.
In May, Bush made the controversial decision to send 6,000 National Guard troops to assist 9,600 Border Patrol agents in stemming the tide of illegal immigration. More than 900,000 illegal immigrants are arrested along the border each year.
By 2008 the president plans to make the Border Patrol the largest federal law enforcement agency -- nearly 90 percent of the agents will be assigned to the Mexican border.
Lt. Mark Williams of the New Mexico National Guard said that manpower, combined with helicopters and infrared-tracking aircraft, were making the job easier.
"That gives us a capability that the ground guys don't have and that is to be able to see the IR heat signature from individuals walking in the desert," Williams said.
The government is spending $5 million on a Web site where cameras will transmit live pictures of remote areas along the border. Visitors to the site will be able to call a toll-free number to report anything suspicious.
ABC News's Mike Von Fremd originally reported this story