'This will not be a mission to build a new wall. 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 this week the state is deploying 80 National Guard troops this week and expects to eventually deploy 250.
Westrup said that the governor's decision to deploy 400 troops is "consistent" with the number requested by the federal government, but didn't say whether federal officials had requested they be assigned to fight transnational crime or to a different assignment.
The governors of Texas, New Mexico and Arizona - all Republicans - applauded Trump's move and quickly began dispatching troops to the border region.
At that time, he added, the federal government will determine whether it has the budget and whether the mission is necessary to continue.
Texas, meanwhile, has sent 250 National Guard troops to the U.S. -Mexico border since Trump made the announcement.
'I'm sorry', Facebook CEO Mark Zuckerberg apologizes over data misuse
Facebook said the commission will last for one year and that membership will be determined in the coming weeks. He's now tweaking that high-minded goal to emphasize positive community-building, not just connectivity.
He says they will not "round up women and children or detain people escaping violence and seeking a better life".
Arizona recently deployed its first 225 troops to its border.
A spokesman for Brown said the location and assignment of troops would "be dictated by the needs on the ground".
The Pentagon has said National Guard troops will not perform a law-enforcement role, and will be armed only for the objective of self-defense.
And the governor insisted in his letter that Trump's public pronouncements on border threats were misguided - pointing to statistics that show the number of detained immigrants in California is at its lowest point in almost 50 years.
California deployed troops to the border under former Presidents George W. Bush in 2006 and Barack Obama in 2010.
In his letter, Brown pointed out that the number of undocumented immigrants apprehended by Border Patrol agents is already the lowest its been in decades. The governor also said in his letter that he wants to make it clear that there is "no massive wave of migrants pouring into California".