Air Force Establishes Expanded National Defense Area Along Rio Grande in South Texas

The U.S. Air Force has announced the creation of a new 250-mile National Defense Area (NDA) in South Texas, following a directive from Secretary of Defense Lloyd Austin. The newly designated zone runs along portions of the Rio Grande River in Cameron and Hidalgo Counties and will be administered as part of Joint Base San Antonio.

The move, ordered under Presidential Executive Order 14167 signed by President Trump, marks the third National Defense Area to be established along the U.S.-Mexico border in recent months and is part of a broader military-led initiative to reinforce southern border security through expanded Department of Defense authority.

“The Secretary of the Air Force, along with Commander, U.S. Northern Command, will coordinate closely to facilitate USNORTHCOM's mission and cooperate on installation matters,” the Air Force said in a press release.

Land for the area was transferred from the International Boundary and Water Commission through the General Services Administration. The NDA designation allows the military to enforce security measures that include the installation of fencing, signage, surveillance equipment, and the temporary detention of trespassers pending transfer to civilian law enforcement.

Under the direction of U.S. Northern Command (USNORTHCOM), Joint Task Force–Southern Border (JTF-SB) personnel will begin operations within the NDA. Their mission includes "enhanced detection and monitoring through stationary positions and mobile patrols," temporary detainment of unauthorized entrants, and support for rapid barrier and infrastructure installation, according to the Air Force.

“This was directed under a presidential order. NDAs are designed to support the Department of Defense’s ongoing mission to secure the southern border in coordination with interagency and partner stakeholders,” the statement said.

The announcement follows the establishment of two earlier NDAs: one in New Mexico on April 21, covering 170 miles of noncontiguous land tied to Fort Huachuca, and another on May 1 in West Texas, covering 63 miles between El Paso and Fort Hancock under Fort Bliss.

All three NDAs are part of a broader homeland defense effort led by USNORTHCOM and reflect a "whole-of-government" approach to securing the southern border.

While the Air Force has stated that all operations will remain in accordance with federal law and in coordination with partner agencies, civil liberties advocates have warned that increased military jurisdiction in civilian areas could blur lines between national defense and law enforcement.

The Air Force emphasized that enforcement in the newly designated South Texas NDA will begin immediately.