Why Trump turned Roosevelt Reservation into a military zone at the southern border

In a move that significantly alters the legal and operational landscape of U.S. immigration enforcement, President Donald Trump has authorized the U.S. Department of Defense to take jurisdiction over federal lands along the southern border, effectively transforming these areas into military-controlled zones. The decision, issued through a presidential memorandum on April 11, 2025, titled “Military Mission for Sealing the Southern Border of the United States and Repelling Invasions,” instructs the secretaries of Defense, Interior, Agriculture, and Homeland Security to begin facilitating the jurisdictional transfer. These lands will now be classified as “National Defense Areas,” a designation typically used during times of war or extreme national security threats.

The administration argues that the directive is essential to reinforce ongoing military-led immigration enforcement operations and to ensure a unified chain of command across critical areas of the U.S.-Mexico border. By placing these territories directly under the control of the Department of Defense, President Trump aims to remove bureaucratic hurdles that have traditionally complicated coordination between military, border patrol, and civilian agencies.

What areas are affected by Trump’s borderland militarization order?

The memorandum specifically names the Roosevelt Reservation, a federally owned strip of land stretching approximately 60 feet wide along parts of the southern border in California, Arizona, and New Mexico, as one of the zones that will fall under military jurisdiction. Historically, the Roosevelt Reservation was established in 1907 by President Theodore Roosevelt to prevent obstructions near the border that might interfere with security or patrols. While relatively narrow—often described as the length of a baseball pitcher’s throw—the reservation spans hundreds of miles and intersects with several active migration corridors.

This land designation will allow for the rapid construction of physical barriers, installation of surveillance systems, and deployment of armed personnel without the need to consult other federal landowners or navigate traditional permitting processes. However, the sweeping nature of the jurisdictional transfer has raised alarm among civil rights groups, legal experts, and environmental advocates, who see the move as a step toward the militarization of domestic immigration policy and a potential bypass of established land management protections.

Could migrants now face more severe legal consequences for crossing into military zones?

One of the most significant and potentially controversial implications of the order involves the legal ramifications for migrants who attempt to cross into the United States via these newly designated military areas. According to Adam Isacson, director of defense oversight at the Washington Office on Latin America, migrants apprehended on land now controlled by the Department of Defense could be charged with trespassing on a military installation—a charge with much more serious criminal implications than the typical federal misdemeanor of “entry without inspection.”

If applied, this interpretation would represent a dramatic escalation in how illegal border crossings are prosecuted. The strategy raises questions about proportionality, due process, and the precedent of treating civilian immigration offenses as military intrusions. It also signals a further blurring of lines between immigration enforcement and national defense, a trend that has accelerated under Trump’s renewed focus on border militarization since the beginning of his second term.

What is the legal basis for using the military to enforce immigration policy?

While the U.S. military is generally prohibited from performing domestic law enforcement functions under the Posse Comitatus Act, there are exceptions when it comes to national emergencies or when operating in support roles to civilian agencies. President Trump’s memorandum frames the situation at the southern border as an ongoing “invasion,” citing threats posed by transnational criminal organizations, human traffickers, and unauthorized migration flows.

This language is consistent with prior declarations of national emergency and the legal justifications used in 2019 and 2020 to redirect Pentagon funds toward border wall construction. However, critics argue that invoking invasion rhetoric to justify military jurisdiction over domestic land sets a dangerous precedent, potentially enabling the erosion of civilian authority in other contexts under the guise of emergency powers.

Despite the administration’s position, the use of military installations to enforce immigration policy remains constitutionally murky and could be subject to legal challenge. Past court rulings have drawn clear lines between military and civilian responsibilities in border security, emphasizing the need to preserve the civil liberties of all individuals within U.S. jurisdiction—including asylum seekers and undocumented migrants.

Is there still a crisis at the southern border justifying this action?

Although the Trump administration continues to assert that the southern border is under siege, data from U.S. Customs and Border Protection tells a more nuanced story. In March 2025, the agency reported just 7,200 migrant encounters—a staggering decline from over 189,000 in the same month a year earlier. Analysts credit the drop to a combination of intensified enforcement by both the U.S. and Mexican governments, including joint patrols, heightened deportation efforts, and stricter visa rules.

Despite the sharp decrease in border crossings, President Trump’s order calls for even greater military presence and operational control. According to Isacson, there are already between four and five uniformed personnel for every migrant apprehended at the border, making it unclear what additional value the new jurisdictional authority would provide. The imbalance suggests that the move may be driven more by political optics and deterrence messaging than by a genuine need for escalated force.

What are the broader implications of declaring borderlands as ‘National Defense Areas’?

Designating swaths of land as National Defense Areas brings with it significant consequences. These areas can be closed to public access, exempted from environmental review laws, and governed by military rules of engagement. This raises concerns not only for migrants but also for indigenous communities, landowners, and conservationists who operate in or near the Roosevelt Reservation and similar areas.

The memorandum directs an initial assessment after 45 days to evaluate military activity on the transferred lands, implying that this could become a long-term framework for immigration enforcement. By setting this precedent, the administration may be laying the groundwork for future expansion of military authority into other aspects of border management, including surveillance, detention, and deportation logistics.

The reclassification also creates logistical challenges for non-defense agencies such as the Department of the Interior and the U.S. Forest Service, which may find themselves sidelined from decision-making on lands they previously managed. This centralization of authority under the Pentagon effectively reorients the U.S. border strategy from a multi-agency civil operation to a defense-dominated mission—redefining the southern border as a military frontier.

How could this move reshape immigration policy going forward?

As President Trump intensifies his second-term immigration strategy, the militarization of the southern border reflects a broader ideological shift that prioritizes deterrence, criminalization, and sovereign enforcement over humanitarian considerations and legal pathways to entry. This development also signals a sharp divergence from past administrations that favored civil law enforcement and interagency coordination.

While it remains to be seen whether this approach will be upheld in court or replicated by future administrations, it undeniably marks a new chapter in U.S. immigration policy—one where the boundaries between civilian governance and military oversight grow increasingly blurred. As federal lands are redefined as National Defense Areas, the symbolic and operational transformation of the U.S.-Mexico border could have long-lasting consequences not just for immigration enforcement, but for the balance of power between civilian and military authority in domestic affairs.