The southern border has been a mess for decades, with government falsely officials insisting they can't do anything about it.  

Illegal immigration into Mexico has always been treated as a crime. If you are not a citizen of Mexico and are caught there without the proper identification, you will be thrown into a Mexican prison.  When Trump became president, he worked with the Mexican government to control the flow of migrants coming up from Central America.   And it worked.  Attempted border crossings slowed down.

From January 2017 through January 2021, through Trump's entire presidency, Border Patrol encountered 2,112,458 people entering the United States illegally through the southern border.

However, the flow changed with the administration.  Only partway through Biden's presidency, as of October 2023, there had been over 9 million illegal entries into the U.S.  Things have only increased since then. December alone saw approximately 300,000 illegal border crossings.

Texas has had enough.
The open border policy has been a disaster for low-income American communities, where resources were already stretched thin.  Texas, with its huge border, finally had enough.  

On January 10, the Texas National Guard seized Shelby Park near Eagle Pass, Texas.  The Biden Administration had ordered Border Patrol agents to use the 47-acre park for processing migrants.  When Texas National Guardsmen seized the park, they began erecting concertina wire as a deterrent.  The Biden Administration ordered Border Patrol to continue using the park anyway, and filed an emergency brief with the Supreme Court, who voted 5-4 to allow federal agents to resume cutting Texas' concertina wire. (source)

This could have been a recipe for conflict between federal Border Patrol agents and Texas Guardsmen.  However, the Border Patrol has stated that they have no plans to dismantle infrastructure put in place by the Texas National Guard.  A senior Border Patrol official told Fox News that the relationship between the Texas National Guard and Border Patrol was strong. They respected each other's jobs, and both intended to provide a secure border.