In a letter addressed to the Secretary of the Department of Homeland Security Kirstjen Nielsen and the Secretary of Defense Jim Mattis, Governor Jerry Brown said California would add 400 personnel to its current total of 250 troops which includes 55 at the California border.

"But let's be crystal clear on the scope of this mission," he wrote. "This will not be a mission to build a new wall. It will not be a mission to round up women and children or detain people escaping violence and seeking a better life."

"And the California National Guard will not be enforcing federal immigration laws."

Instead, they would support operations targeting transnational criminal gangs, human traffickers and illegal firearm and drug smugglers along the border, he added, "priorities for all Americans -- Republicans and Democrats."

He added that "there is no massive wave of migrants pouring into California," citing statistics that showed immigrant apprehensions on the border in 2017 were at a near 50-year low.

California is at the forefront of what opponents call the "Resistance" to President Trump's administration, with the heavily Democratic state suing the federal government over numerous issues including the rollback of environmental regulations.

US Attorney General Jeff Sessions, for his part, has sued the state over three statutes that support cities and counties that refuse to hand over unauthorized immigrants to federal immigration authorities for prosecution or expulsion.

Texas announced Tuesday it would send more than 1,000 National Guard troops to the US-Mexico border, in response to President Donald Trump's call for the military deployment to the southern frontier.

The border state of Arizona has also responded to the federal request, deploying 225 members of its Guard on Monday.

The deployments came after the US Defense Department last week signed an order calling for as many as 4,000 National Guard personnel to assist at the southern border.

Trump has indicated he might keep troops at the border until his promised border wall is built.