Arizona Gov. Doug Ducey said Monday that 225 members of the state's National Guard were heading to the U.S.-Mexico border to support President Donald Trump's call for troops to fight drug trafficking and illegal immigration.
More of the state's Guard members will be deployed on Tuesday, said Ducey, a Republican.
The Arizona troops were being sent after Texas announced Friday it would send 250 National Guard members and helicopters took the first of them to the border.
Trump said last week he wants to send 2,000 to 4,000 National Guard members to the border.
New Mexico's Republican governor has said her state would take part in the operation but no announcement has been made on deployment. California Gov. Jerry Brown, a Democrat, has not said if the state's Guard members will participate.
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.
Defense Secretary James Mattis last Friday approved paying for up to 4,000 National Guard personnel from the Pentagon budget through the end of September.
A Defense Department memo said the National Guard members will not perform law enforcement functions or "interact with migrants or other persons detained" without Mattis's approval.
It said "arming will be limited to circumstances that might require self-defense" but idid not further define that.
After plunging at the start of Trump's presidency, the numbers of migrants apprehended at the southwest border have started to rise in line with historical trends.
The Border Patrol said it caught around 50,000 people in March, more than three times the number in March 2017.
That's erased a decline for which Trump repeatedly took credit. Border apprehensions still remain well below the numbers when former Presidents George W. Bush and Barrack Obama deployed the Guard to the border.