0956 GMT July 19, 2018
The Texas National Guard said on Friday it would send 250 troops to the border within 72 hours, while Arizona's governor said he would send 150 soldiers next week, presstv.com reported.
Every US state has a National Guard unit, which consists of several thousand reserve forces under mixed state and federal control since 1933.
"The Texas national guard is preparing to immediately deploy with supporting aircraft, vehicles and equipment to the Texas-Mexico border," Brigadier General Tracy Norris, the commanding general of the Texas National Guard, told reporters at a briefing.
"This deployment has begun with the movement of equipment and troops today. Within 72 hours the Texas military department will have 250 personnel along with ground surveillance vehicles as well as light and medium aviation platforms," she added.
US Defense Secretary James Mattis signed an order for up to 4,000 National Guard personnel to patrol the US-Mexico border through September 30, 2018.
The National Guard troops would support US Border Patrol agents and be under the command and control of their respective state governors, Mattis said.
Border Patrol is a federal law enforcement agency under the jurisdiction of the Department of Homeland Security.
Mattis and Homeland Security Secretary Kirstjen Nielsen said the decision came after their departments "identified security vulnerabilities that could be addressed by the National Guard."
"We will continue to work with the governors to deploy the necessary resources until our nation's borders are secure," they said in a joint statement.
Trump said on Thursday that the final deployment would range from 2,000 to 4,000 troops, and he may keep many personnel on the border until his planned border wall is built, suggesting the deployment will be a lengthy mission.
Mexican President Enrique Pena Nieto has sharply rebuked US President Donald Trump over his plan to send National Guard troops to the border with Mexico.
The move has heightened tensions with Mexico and drawn a sharp rebuke from the country’s President Enrique Pena Nieto.
In an unusually combative address on Thursday, a stern-looking Pena Nieto urged Trump to stop sowing discord between the two nations and demanded a more respectful tone in bilateral relations.
Pena Nieto and Trump have had a strained relationship ever since the president launched his election campaign in 2015 with the claim that some Mexican migrants are criminals and rapists.
Trumo also promised to build a border wall and make Mexico pay for it. Mexican officials have adamantly rejected the payment for the proposed wall.