A New Phase in Border Militarization: Trump’s “National Defense Areas”

New “National Defense Areas” in Texas and New Mexico are escalating a diplomatic crisis with Mexico, creating legal turmoil in U.S. courts, and even leading to deaths among active-duty troops

Soldiers patrol along the border wall near Sierra Blanca, Texas. (Photo credit: Army Pfc. Malik Waddy-Fiffee)

In the last three weeks, two militarized national defense areas have been rapidly established at the southern U.S. border, sowing chaos and jeopardizing historical water treaties with Mexico.

In April, the Department of the Interior transferred 170 miles of the Roosevelt Reservation—a 60-foot-wide federally owned strip of land along the border between New Mexico and Mexico—to the Defense Department, which placed it under the jurisdiction of Fort Huachuca, an army base in Arizona.

On May 1, the Department of Defense’s U.S. Northern Command, which oversees President Trump’s southern border deployments, announced a second “national defense area” in El Paso, Texas.

This militarized zone begins at the American Dam in El Paso and extends 63 miles southeast to Fort Hancock, Texas. Last week, the International Boundary and Water Commission (IBWC) transferred the land to the Department of Defense. The land is now under the jurisdiction of Fort Bliss in El Paso.

In a written statement to The Border Chronicle, a NorthComm spokesperson explained that the new Texas National Defense Area “comprises 2,000 acres of land, including the banks and bed of the Rio Grande River.”

In Texas, where the Rio Grande serves as the international boundary with Mexico, the transfer of IBWC land to the U.S. military raises significant diplomatic concerns for Mexico over its historic water treaties with the U.S. It further escalates Trump’s aggressive stance toward Mexico, a neighboring ally, as he deploys thousands of active-duty soldiers and military hardware to the southern border.

“Mexico is going to be looking at this and will be thinking that it has the potential to impact its sovereignty,” said Stephen Mumme, emeritus professor of political science at Colorado State University and an expert on U.S.-Mexico water relations. “Depending on how it is enforced, I don’t rule out the fact that the Defense Department, which has been told to do this, doesn’t try to assert certain authority over the IBWC. But the commission cannot surrender its treaty authority under international law.”

Trump is increasingly wielding shared water rights with Mexico as a weapon. In March, for the first time since the U.S.-Mexico water treaty was established in 1944, the United States refused to release water from the Colorado River to Tijuana, Mexico. As Trump threatened more tariffs, Mexico pledged in late April to release water to the Rio Grande, despite a historic drought in northern Mexico and reservoirs at just 15 percent capacity.

Additionally, as Trump has deployed nearly 10,000 active-duty soldiers, Stryker Combat vehicles, and military aircraft to the southern border, he has threatened to send drones and U.S. troops into Mexico to combat drug cartels, which Mexican president Claudia Sheinbaum has repeatedly rebuffed. “Sovereignty is not for sale,” Sheinbaum said at an April rally, recounting one of her conversations with Trump. “We can work together, but you in your territory and us in ours.”

Since 1889, the IBWC, a binational organization with offices in Ciudad Juárez, Chihuahua, and El Paso, has overseen binational water treaties, alleviated bilateral tensions over shared water resources, and managed the Rio Grande. Less than two weeks before the IBWC’s land transfer to the military, the agency’s U.S. commissioner, Maria Elena-Giner, was forced to resign by the Trump administration, even though she had made progress on binational agreements and infrastructure projects at the underfunded agency. Giner was replaced by Chad Macintosh, a former director of environmental compliance for the Ford Motor Company and an appointee to the Environmental Protection Agency under the first Trump administration.

Frank Fisher, public affairs chief for the U.S. IBWC, stated that the agency is holding daily meetings with the military to create a memorandum of understanding. “We do not expect this order to negatively impact our flood control, water management, or other important missions along the Rio Grande,” he said.

Fisher added that the land transfer would last three years, but that “it can be shortened or extended.”

The US Army did not respond to a Border Chronicle request for information on the land transfer.

Requests for comment from the Mexican side of the IBWC, the Comisión Internacional de Límites y Aguas in Ciudad Juarez, went unanswered. Fisher said, “We have not heard anything from the Mexican side of the commission” regarding the land transfer to the U.S. military.

The Border Chronicle also sought comment from Mexico’s Secretary of Foreign Affairs, but the agency did not respond by publication time.

Over the decades, since the George W. Bush administration, Mexico has quietly lodged diplomatic complaints about the U.S. constructing border barriers near the Rio Grande, according to Mumme. “The treaty is very clear that if either country is going to build infrastructure near the river, it requires the consent of both countries. But Mexico has never agreed,” he said. “Because these structures can affect the river flow and contribute to flooding.”

The issue has worsened with Texas constructing its own fences and barriers and deploying buoy barriers on the Rio Grande, in defiance of both the United States and Mexico, he added.

To date, Mexico has shown considerable restraint, Mumme said, attempting to work quietly through diplomatic channels. “That is where they’ve been for the last decade, but with the transfer of IBWC land to the Defense Department, this could heighten concerns,” he said.

National Defense Areas as of May 8, 2025. (Graphic credit: Eugenio del Bosque)

Chaos in the Courts, and Soldiers Harmed

The national defense areas were established under an April 11 presidential memo titled the “Military Mission for Sealing the Southern Border of the United States and Repelling Invasions,” which capitalizes on the false premise that the border is under invasion. President Trump was able to create the defense areas without the approval of Congress, because he declared a national emergency at the southern border upon taking office in January. The falsehood that the border is under invasion was propagated by Trump and MAGA allies during his presidential campaign, conflating people legally seeking asylum with “invaders.” Migration apprehension rates began declining during the last year of Biden’s presidency, and currently, border crossings are at their lowest in more than 20 years.

Despite this reality, the Trump administration has continued to deploy active-duty soldiers to border communities and place public lands under military control. The national defense areas are considered military installations, allowing the Defense Department to install surveillance systems, build border walls, and exclude unauthorized people. Anyone detained in these militarized zones faces federal trespassing charges for being on a military installation, which can result in up to a year in jail and a $100,000 fine. Undocumented border crossers already charged with illegal entry, facing penalties of up to six months in jail and up to $5,000 in fines, will also receive additional federal charges if detained in a national defense area.

Signs posted at the New Mexico defense area indicate that it is “restricted Defense Department property and that all people who enter may be detained and searched. The signs also forbid unauthorized photography, note-taking or mapmaking of the area,” The Washington Post reported.

Trump is increasingly pushing for the military to engage in domestic law enforcement duties, such as immigration enforcement. Under the Posse Comitatus Act of 1878, the U.S. military cannot directly enforce immigration laws or apprehend migrants at the border. Migrants are considered civilians, and federal law bars active-duty troops from carrying out most law enforcement activities on U.S. soil. But under these new national defense areas, soldiers can arrest and detain anyone who trespasses in the militarized zones.

The rapid transfers of land to military control, without clear instructions or guidelines for federal agencies, have created confusion in the courts and endangered military personnel. In April, two young Marine Corps soldiers deployed to the New Mexico defense area from California were killed, and another was seriously injured while trying to avoid a head-on collision on Highway 9 in New Mexico as they followed a convoy led by a Border Patrol vehicle, as reported by Stars and Stripes.

Last Friday in New Mexico, about “100 weary-looking men in shackles” appeared in a U.S. district court, charged with the unprecedented federal trespassing charge under Title 50, the national defense and intelligence code. This scenario caused confusion among the magistrate judge, defense attorneys, and the defendants, who claimed they had no idea they had entered a militarized zone, according to The Washington Post.

This week, however, U.S. Attorney Ryan Ellison in New Mexico clarified that defendants could be found guilty regardless of whether they saw the posted warning signs. Ellison said he would prosecute the cases aggressively, according to the Post, characterizing the effort as the “first large-scale use of a novel criminal statute.”

Despite the chaos and harm caused to diplomatic relations with Mexico, a government source, who asked to remain anonymous for fear of reprisal, told The Border Chronicle that the government plans to create additional national defense areas in Arizona and California. The source did not provide a timeline.