On Friday, Defense Secretary Jim Mattis signed a memo that authorized the federal government to pay for the potential deployment of up to 4,000 National Guard troops for the border mission through September. That's more than 33,000 more than in March of past year. That compares with 79,061 the prior year - and more than 725,000 in 2000.
Administration officers have talked about that rising numbers of people being caught on the southern border, whereas in keeping with seasonal traits now, require an instantaneous response.
That was confirmed Monday by Ducey's office, which said in a statement that Arizona guardsmen would act in "mission-enhancing capabilities" that will free up Border Patrol agents in the field.
The Republican governor accused the federal government of ignoring the border "for almost a decade".
Apprehensions are nonetheless correctly beneath their historic traits all through the phrases of former presidents George W. Bush and Barack Obama, every of whom moreover deployed the Guard to the border.
Over the weekend, the Arizona National Guard activated a team of planners who will coordinate the arrival of new troops.
National Guard members have started arriving at the US-Mexico border, with more expected as federal government officials continue to discuss what they will do about illegal immigration.
Abbott said he would add about 300 Guard members a week to the 250 members whose deployment was announced Friday until the total number reaches at least 1,000 troops.
New Mexico's Republican governor says her state will participate as well.
On the same day, Arizona Gov. Doug Ducey (R) said the Arizona National Guard would send 338 troops to the southern border.
The Arizona deployments began Monday. He says he's pleased they will play support roles only.
"I don't think this is a partisan issue or an identity issue", he said.
The placement of soldiers along the border has raised some concerns about militarizing the area.
Sessions' visit comes after President Donald Trump said last week he wants to send 2,000 to 4,000 National Guard members to the border.
"The state of Arizona must not be used as a political pawn that will leave visitors questioning the safety of our state", he said in his letter to Ducey. "It gets more boots on the ground and they serve in a support capacity, which they'll be very good at".
Brown's spokesman, Evan Westrup, said Monday that California is still reviewing President Trump's request for use of the state's National Guard members. He plans to work with federal officials to decide how long the National Guard stays at the border.
The troops will not have law enforcement powers but will only provide support.
It said "arming will be limited to circumstances that might require self-defense" but did not further define that.
Trump has said he wants to use the military at the border until progress is made on his proposed border wall, which has mostly stalled in Congress.
But critics, including Rep. Raul Grijalva, D-Arizona, said a military deployment was more likely to "do irreversible damage" than improve the situation on the border.