After days of speculation, California decided Wednesday that it will comply with federal requests to deploy National Guard personnel to the border California shares with Mexico.
He sent a defiant letter to the Trump administration on Wednesday, saying the additional troops will only supplement the staffing of California's ongoing program to combat transnational crime.
The program is now staffed by 250 personnel statewide, including 55 at the California border.
Instead, Brown said the troops would join an existing program to combat transnational drug crime, firearms smuggling and human trafficking.
"But let's be crystal clear on the scope of this mission", Brown wrote in a letter to U.S. Secretary of Homeland Security Kirstjen Nielsen and Defense Secretary James Mattis. Jerry Brown accepted President Donald Trump's call to send the National Guard to the Mexican border, but rejected the White House's portrait of a burgeoning border crisis and insisted that his troops will have nothing to do with immigration enforcement.
Trump last week ordered a military mobilization along the border with Mexico, accusing Democrats of encouraging illegal immigration and failing to protect the country from a flood of illegal migrants.
Not all 400 troops will head to the US-Mexico border and none will arrest or deport immigrants.
Unlike Republican governors in other border states, Brown disagreed with Trump's portrayal of a border spiraling out of control, noting that Border Patrol arrests fell to the lowest level a year ago since 1971 and that California accounted for only 15 percent of the agency's arrests on the Mexican border.
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The governor stressed in his statement that the troops will not be used to "round up women and children or detain people escaping violence and seeking a better life".
The state's guardsmen provided "targeted assistance" in 2006 under then-President George W. Bush and in 2010 under President Obama.
It will take some time before Guard troops can be deployed. Customs and Border Protection report, there was a 37-percent increase overall in March, when compared to February and a 203 percent increase compared to March of past year.
Brown said the deployment will happen pending review and approval of the federal government.
Brown had been quiet about what his plans were with regard to Trump's announcement until now.
Governors act as the commander-in-chief of their respective state guards, which is why Trump isn't authorized to direct the troops as he sees fit.