The U.S. Department of Justice issued a legal opinion on Friday granting the military expanded authority to detain migrants accused of trespassing within specific zones along the southern border. These areas, designated as “National Defense Areas” (NDAs) by the second Trump administration, are intended to deter illegal immigration and are currently closed to civilian access.
While the Posse Comitatus Act typically restricts military involvement in domestic law enforcement, the Justice Department’s Office of Legal Counsel concluded that military personnel may now arrest individuals who exit these NDAs before they can be officially apprehended for trespassing. Deputy Assistant Attorney General William Hyde stated that this use of military personnel does not violate the act, citing express statutory authorization and the traditional protective powers afforded to military commanders.
The administration has established six such defense areas across Arizona, California, New Mexico, and Texas. According to the new opinion, the military may designate additional zones in the future. Because these areas often encompass land that does not resemble a traditional military base, the Defense Department has installed bilingual signage warning that entry is prohibited.
U.S. Northern Command has confirmed that service members are authorized to apprehend trespassers within these zones and transfer them to the appropriate law enforcement agencies. The Justice Department began prosecuting individuals apprehended in these areas in April 2025, with hundreds of charges filed since. Typical charges include violating military security regulations or unauthorized entry onto military property, both of which are classified as misdemeanors, though other border-related charges may also apply.
The Pentagon prioritized the U.S.-Mexico border during the early days of President Trump’s second term, deploying over 20,000 service members to the region. Currently, the military’s southern border Joint Task Force consists of 8,000 personnel and has recorded 161 detentions within the designated national defense zones.
The legal opinion remains advisory and does not establish formal legal precedent. This initiative is part of a broader strategy that includes the effective closure of the asylum system for those entering the country illegally. These enforcement measures have coincided with a significant decline in border crossings.
Official data shows that Border Patrol recorded fewer than 240,000 migrant apprehensions in fiscal year 2025, a sharp decrease from the 1.5 million and 2 million recorded in fiscal years 2024 and 2023, respectively. This downward trend has continued into fiscal year 2026, with 81,000 apprehensions reported with two months remaining in the fiscal period.
Since then, the Defense Department says more than 20,000 service members have served deployments on the border.
The number has fallen even more in fiscal year 2026, with Border Patrol recording 81,000 apprehensions, with two months left.
The crackdown has coincided with a dramatic drop in illegal crossings there.
Source: CBS News
