California National Guard 'Will Promptly Review' Trump's Troop Deployment To Mexican Border

California Gov. Jerry Brown has not shied away from taking on President Donald Trump in the immigration debate.

On the president’s proclamation Wednesday deploying National Guard troops to the U.S.-Mexico border, though, the governor’s reaction so far is muted.

Brown’s office referred request for comment to the California National Guard, which says it will “promptly“ review what it calls a “request” from the Department of Homeland Security to determine how it can best assist its federal partners.

“We look forward to more detail, including funding, duration and end state,“ Lt. Col. Tom Keegan, added in a statement. “End state“ refers to what would be considered mission success.

California participated in the previous two deployments of National Guard troops to the Mexican border, by President George W. Bush in 2006 and President Barack Obama in 2010.

The state currently has just over 50 National Guard troops providing support to the Southwest Border — all from its Counterdrug program.

Homeland Security Secretary Kirstjen Nielsen said she had been working with governors of the southwest border states to develop agreements on where and how many Guardsmen will be deployed.

She suggested some troops could begin arriving as soon as Wednesday night, though other administration officials cautioned that details on troop levels, locations and timing were still being worked out.

Trump has been frustrated by slow action on building his "big, beautiful wall" along the Mexican border — the signature promise of his campaign — as well as a recent uptick in illegal border crossings, which had plunged during the early months of his presidency, giving Trump an accomplishment to point to when he had few.

Federal law prohibits the use of active-duty service members for law enforcement inside the U.S., unless specifically authorized by Congress. But over the past 12 years, presidents have twice sent National Guard troops to the border to bolster security and assist with surveillance and other support.

One congressional aide said that lawmakers anticipate 300 to 1,200 troops will be deployed and that the cost was expected to be at least $60 million to $120 million a year. The Pentagon would probably need authorization from Congress for any funding beyond a few months, said the aide, who wasn't authorized to speak publicly and spoke on condition of anonymity.

Under the mechanism the administration is looking to use, the Guard would not be mobilized as a federal force. Instead, governors would control the Guard within their states.

Governors of the other three U.S. states bordering Mexico were largely supportive of the move

The Associated Press contributed to this report