Meanwhile, Defense Secretary Jim Mattis signed a memo Friday that authorized the potential call-up of up to 4,000 National Guardsmen for the mission though it remains unclear exactly how many Guardsmen will be mobilized to support the border mission.
"Together, the Departments of Homeland Security and Defense are committed to using every lever of power to support the men and women of law enforcement defending our nation's sovereignty and protecting the American people," Mattis and Secretary of Homeland Security Kirstjen Nielsen said in a joint statement.
Late on Friday, Texas and Arizona announced that they would each make initial deployments of about 150 guardsmen to support the new border security mission. The governors of California and New Mexico have not announced whether they will participate in the support mission unveiled by the Trump administration earlier this week.
"The Texas National Guard is preparing to immediately deploy with supporting aircraft,vehicles and equipment to the Texas-Mexico border," said Brig. Gen. Tracy Norris, assistant deputy adjutant general of the Texas Military Department.
She said 150 Texas Guardsmen will join 100 guardsmen who had been supporting previous border security operations along the border with Mexico.
"This initial phase of deployment will include command and control, coordination cells and operational planning support of the federal entities already on the border," said Norris. "Follow-on forces will move to the border once mission requirements and locations are finalized."
The Arizona National Guard also announced on Friday that it had activated a team of planners who would coordinate the deployment of 150 guardsmen to the border next week. Gov. Doug Ducey confirmed the news on Twitter.
"These service members will provide mission-enhancing capabilities that allow Customs and Border Protection personnel to provide more law enforcement officers to the field," said an Arizona National Guard statement.
"The Guard will provide air support, reconnaissance support, operational support, construction of border infrastructure, and logistical support. This will allow CBP to increase operational control of the region."
The governors of California and New Mexico have not announced whether they will participate in the support mission unveiled by the Trump administration earlier this week.
On Friday, Mattis signed a memo that authorized the federal government to pay for the deployment of up to 4,000 National Guardsmen under what is known as Title 32. Under that authority, state governors will call up guardsmen for the mission and maintain their command and control, but their operations will be paid for by the federal government.
The memo signed by Mattis recommended that he "Authorize and approve up to 4,000 National Guard personnel in Federal pay and duty status, under title 32 U.S. Code, section 502, to conduct operations in support of DHS southern border security missions ... through September 30, 2018."
It remains unclear how many additional guardsmen could be deployed by the four southwestern border states.
The memo also said that National Guard personnel “will not perform law enforcement activities or interact with migrants or other persons detained by DHS personnel without your approval: arming will be limited to circumstances that might require self-defense.”
The potential call up of as many as 4,000 National Guardsmen is in line with Trump's estimate Thursday that he would like to see between 2,000 to 4,000 National Guard troops deployed to the border.
Also unclear is how long the deployments could last; Trump has said wants National Guardsmen to guard the U.S. border with Mexico until a border wall is built.
The initial deployments of Texas and Arizona National Guardsmen are in line with what the Pentagon's chief spokesperson had outlined at a Thursday press conference.
"The National Guard's efforts will include aviation, engineering, surveillance, communications, vehicle maintenance and logistical support," said White.
President Barack Obama deployed 1,200 guardsmen in 2010 as part of a similar mission called Operation Phalanx.