Updated at 5:50 p.m. ET
California Gov. Jerry Brown agreed Wednesday to deploy 400 National Guard troops in response to a Trump administration request to border state governors. But in a letter sent Wednesday, Brown says California troops will not enforce federal immigration laws or build a border wall.
Brown's letter said the California Guard will "do what it does best": focus on transnational criminal gangs, human traffickers, and drug and firearms smugglers throughout the state.
"Let's be crystal clear on the scope of this mission," Brown wrote in the letter to Defense Secretary Jim Mattis and Homeland Security Secretary Kirstjen Nielsen. "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."
The Trump administration wants 4,000 troops along the U.S.-Mexico border to fight drug trafficking and illegal immigration.
California's deployment will happen pending review and approval by the federal government.
During a White House press briefing on Wednesday, press secretary Sarah Sanders told reporters the administration was "glad to see California Gov. Jerry Brown work with the administration and send members of the National Guard to help secure the Southern border."
And in an email to NPR, a DHS spokesman wrote, "The Secretary recently spoke with Gov. Brown. She is pleased to have the support of all four border governors to help secure our southwest border. Issues of border security require the partnership of the federal government and our state and local allies to be successful."
"More eyes in the sky"
Meanwhile, the first members of the National Guard in Texas have already made their way to the U.S-Mexico border. The Laredo Border Patrol sector says it would welcome the help.
The Laredo section of the Texas-Mexico border spans 170 miles and contains no walls or fences.
Border Patrol Chief Greg Burwell said it is a challenge to keep tabs on all of it.
"Access to the actual river, to the border, is difficult for us. Even in the best of times — when all of our cameras are working — we can see roughly 30 percent of our area of operation," he said. There are only 4 miles of paved road along the Laredo segment of the border.
On Saturday, five planners from the National Guard arrived in the Laredo Border Patrol sector, where they heard requests and operational input from Burwell and his staff.
"There's always a dialogue back and forth between the Defense Department and U.S. Customs and Border Protection," Burwell said. "We did a data call saying what we needed."
Burwell said National Guard troops will act in an administrative and support capacity: clearing roads, maintaining vehicles and scanning for border crossings by air. He said that Border Patrol agents normally don't participate in trainings with the Defense Department because their duties are "really disparate."
"The way things stand right now, National Guard troops won't be working in an official law enforcement capacity," Burwell said. "So the information I've got so far is that they won't be armed, and they won't be in roles where they would interact with the people that we're arresting, that we're looking for, the criminals, things like that."
The Laredo Border Patrol sector has requested 270 National Guard troops, which Burwell expects will arrive "very soon," though he did not have a precise date. He said most of the Southwest border sectors will receive National Guard support.
"We lack in infrastructure. We have a dearth of manpower. So we welcome the help," he said. "More eyes in the sky for us, more help on the ground, more behind-the-scenes type stuff is a really big deal for us."
Other border states are also deploying National Guard troops.
In Arizona, Gov. Doug Ducey has so far sent 338 troops to the border, which KJZZ reports are "expected to give air and logistical support, help with reconnaissance and work on border infrastructure." Although New Mexico Gov. Susana Martinez has — as the Santa Fe New Mexican reports — "been critical in the past of the president's approach to border security and immigration," her office said the state is deploying 80 National Guard troops this week and expects to eventually deploy 250.