The Department of Defense has established a second National Defense Area (NDA) along the U.S.-Mexico border, extending a 53-mile stretch from El Paso to Fort Hancock, Texas. The area, now part of Fort Bliss, allows U.S. troops to temporarily detain migrants suspected of unlawful entry before transferring them to civilian law enforcement. This follows a similar zone designated last month along a 170-mile stretch of New Mexico border land now administered by Fort Huachuca in Arizona.
Why is the Pentagon expanding military zones at the border?
The Defense Department said the new designation increases the military’s ability to support border enforcement operations. Gen. Gregory Guillot, head of U.S. Northern Command, said the move enhances the military’s reach and capacity to intercept unlawful activity along the southern border. Troops will use stationary observation points and mobile patrols to monitor the terrain and report activity to Border Patrol.
“This is the second area in which Joint Task Force – Southern Border service members who are already detecting and monitoring through stationary positions and mobile patrols nearby can now temporarily detain trespassers until they are transferred to an appropriate law enforcement entity.”
Gen. Gregory Guillot, Commander, U.S. Northern Command
How does the new military zone affect migrants?
Individuals crossing these defense zones may face federal charges for illegal entry and trespassing on military property. In New Mexico, the U.S. Department of Justice recently charged more than two dozen migrants under these provisions after military aircraft detected them. Although military personnel did not conduct arrests in that case, the designation allows troops to briefly detain individuals and provide medical aid while awaiting transfer to civilian custody.
How does this shift affect the role of US troops at the border?
The Trump administration has expanded the military’s border presence since January. The Pentagon stationed nearly 8,000 active-duty personnel along the U.S.-Mexico border. This includes combat units from the Fourth Infantry Division and additional surveillance assets such as Navy ships and reconnaissance aircraft.
Designating NDAs classifies the land as part of an active military installation, which provides a legal framework that permits limited troop involvement in detaining migrants until transfer to civilian authorities, sidestepping typical restrictions under the 1878 Posse Comitatus Act.
What role does Fort Bliss play in the new zone?
Fort Bliss, one of the Army’s largest installations, now administers the newly designated El Paso NDA. Stryker armored vehicles patrol the area, outfitted with signage to notify those approaching that they are entering a military base. Maj. Geoffrey Carmichael, a Joint Task Force–Southern Border spokesman, confirmed that surveillance will include camera systems and foot patrols.
How long will the military zones remain in place?
According to the Army, the land designated as an NDA in New Mexico will remain under military control for at least three years. The agency has yet to specify an end date for the El Paso zone. Both regions function as extensions of adjacent military bases and could potentially serve as prototypes for additional militarized areas if mandated.
What is the broader policy context?
The military zones are part of a broader strategy by the Trump administration to intensify border control through the use of defense assets. Since his return to office, Trump has prioritized direct military involvement in immigration enforcement, arguing that it deters illegal crossings. According to U.S. Customs and Border Protection, border encounters dropped sharply in FY2025, falling more than 70% compared to last year.
