U.S. Troops Begin Detaining Migrants in National Defense Zones Along Southern Border, Marking Sharp Expansion of Military Role
Troops U.S. military personnel have begun detaining migrants accused of trespassing into newly established national defense zones along the southern border, marking a significant expansion of the armed forces’ direct involvement in border enforcement. The development, announced by authorities on Wednesday, reflects a shift under the Trump administration’s aggressive border security strategy.
Troops Last week, U.S. Army Lieutenant Colonel Chad Campbell detailed the first instance of such military detentions, which occurred near Santa Teresa, New Mexico. According to Campbell, three individuals were observed crossing a fortified barrier into U.S. territory. Military personnel intercepted the migrants, ordered them to remain in place, and detained them briefly until U.S. Customs and Border Protection (CBP) agents arrived — a process that took approximately three minutes.
Troops The three individuals were among more than 1,400 migrants who have now been charged under new federal guidelines for illegally entering militarized zones created under President Donald Trump’s border security policy.
While the Posse Comitatus Act typically bars the military from engaging in civilian law enforcement activities on American soil, a legal loophole known as the “military purpose doctrine” permits limited involvement under specific conditions. The Trump administration is now testing the boundaries of that doctrine in its effort to reinforce the U.S.-Mexico border.
President Trump has authorized the establishment of two National Defense Areas (NDAs) — one in New Mexico and another along a 60-mile stretch of western Texas between El Paso and Fort Hancock. The federal government has transferred control of these lands from the Department of the Interior to the Department of Defense for a three-year period. These zones are marked by increased security presence and expanded military oversight.
At a news conference held in El Paso on Wednesday, military spokesperson Geoffrey Carmichael confirmed that the administration intends to establish additional defense zones along the southern border. “I won’t speculate to where those are going to be.”
Supporters of the initiative, including federal prosecutors and border officials, argue that these defense zones enhance collaboration between military forces, CBP, and other federal agencies — bolstering efforts to deter unlawful border crossings and smuggling operations.
However, the approach is drawing legal challenges and criticism. Defense attorneys and some judges are raising concerns about the fairness and legality of prosecuting migrants under national security statutes — particularly when many are unaware they’ve entered designated defense zones.
In New Mexico, a judge recently dismissed over 100 national security-related charges filed against migrants for that very reason, while allowing illegal entry charges to proceed.
Despite the legal setbacks, U.S. Attorney Justin Simmons, who oversees the western Texas region, stated his office would continue pursuing military trespassing cases.
The intensifying military role at the border coincides with mounting public opposition to the administration’s immigration tactics. On the same day the military role was publicly outlined, dozens of mayors from across the Los Angeles region jointly urged the federal government to halt immigration raids that have reportedly created widespread fear and unrest in their communities.
President Trump has also ordered an additional 2,000 National Guard troops to be deployed in response to growing immigration-related protests in Los Angeles. That brings the total number of National Guard personnel assigned to federal orders for the protests to over 4,100. The Pentagon had already stationed around 700 Marines in the region to support crowd control and logistics.
The Trump administration’s strategy reflects a broader pattern of militarization of immigration enforcement — a move that critics argue blurs the line between national defense and domestic law enforcement, while raising serious constitutional and humanitarian questions.
As legal battles over the use of military authority to police immigration unfold, and as new defense zones continue to be proposed, the U.S.-Mexico border is becoming not only a frontline in immigration enforcement but also a testing ground for how far the military’s role in civilian matters can stretch.