Updated at 10:20 a.m. on Friday

President Trump told reporters on Air Force One that he wants to send between 2,000 and 4,000 National Guard members to the southern border with Mexico "and we'll probably keep them, or a large portion of them, until such time as we get the wall."

It was the first time Trump attached numbers to his plan to put the National Guard on the border . He said his administration is still studying the potential cost.

Trump's decision to use the National Guard to deter illegal immigration and drug trafficking is drawing praise from some quarters and criticism from others.

Texas Gov. Greg Abbott, in a statement issued Wednesday, welcomed the president's announcement.

"My top priority as Governor is ensuring the safety and security of Texans, and securing our southern border has always been essential to that mission. In my time as Governor, Texas has maintained a continuous presence of National Guard members along the border, and we've added hundreds of permanent Department of Public Safety troopers to the region," said Abbott, a Republican.

Two other GOP governors supported Trump's decision. Arizona Gov. Doug Ducey welcomed the National Guard deployment, saying "Washington has ignored this issue for too long and help is needed." New Mexico Gov. Susanna Martinez expressed her full support, according to her spokesman as quoted by the Las Cruces Sun News.

As the Sacramento Bee reports , California officials are less enthusiastic.

California Gov. Jerry Brown has not made any public comment. In a statement offered on behalf of the governor's office, a spokesman for the California National Guard, Lt. Col. Tom Keegan said the request from the Department of Homeland Security "will be promptly reviewed" by state officials. "We look forward to more detail, including funding, duration and end state," Keegan said.

There was mixed reaction from the border region.

The mayor of El Paso, Texas, Dee Margo, a Republican, told Morning Edition , said, "[We] already have a fence that was established under the Bush administration that runs through our city."

MARGO: What I would love to see is a better understanding of what truly goes on on the border. When I hear even in East Texas and things where there are — you know, there are some folks who are quite xenophobic. They don't understand what's going on. We understand. Come down here and understand. Now, there are pockets where you have issues. But our issues are not significant related to drug trade or otherwise. There are still issues related to human trafficking that most people know on a national and an international basis. But for the most part, as I say, we're the safest city in the United States.GREENE: What do you think this administration doesn't understand yet about the border and about immigration?MARGO: Well, for instance, we give in-state tuition to Mexican nationals in Texas. It is imperative that we create a middle class in Mexico so we're not having the migration north on jobs and — that type of situation at all. We're a trading partner. It's commerce. It's family. It's our entire culture. People don't understand it until they come here.

As Carlos Morales of Marfa Public Radio reported on All Things Considered , Texas already has some National Guard troops performing surveillance on the border.

Morales reports that the mayor of the border town Presidio, John Ferguson, wouldn't mind the Guard's presence, but he does want some accountability from the federal government.

Ferguson added, "Depending on how long the National Guard would be stationed on the border, I think you need to be able to say, OK what effect is this presence having on the border?"

In Mexico, Trump's decision was met with derision and sarcasm.

On Thursday, Mexican President Enrique Peña Nieto countered Trump's remarks on immigration and the border in a video statement defending "the dignity of Mexico."

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