US troops could detain migrants under proposed militarized border zone

• Trump administration officials considered establishing a temporary military-controlled zone along the U.S.-Mexico border. The zone would span 60 feet of federal land.
• Over 10,000 active-duty troops are already engaged in border security efforts, with recent deployments including armored vehicles and a U.S. Navy destroyer.
• Illegal crossings declined to 28,654 in February 2025 from 124,522 in December 2024, according to U.S. Customs and Border Protection. Administration officials attributed the drop to increased military presence and stricter enforcement, though migration patterns fluctuate seasonally.

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The Trump administration will review a plan to establish a military-controlled buffer zone along the U.S.-Mexico border. According to U.S. officials, the plan would authorize the military to temporarily hold migrants who cross illegally while awaiting transfer to law enforcement.

If approved, the move would mark the most significant military involvement in border enforcement under Trump, raising legal questions about the Posse Comitatus Act, which limits active-duty troops from engaging in domestic law enforcement.

Officials said the administration is exploring ways to classify the buffer zone as a military installation, framing migrant apprehensions as trespassing rather than law enforcement actions.

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Where would the buffer zone be established?

The proposed buffer zone would span a 60-foot-wide strip of federal land along the southern border, known as the Roosevelt Reservation.

Former President Theodore Roosevelt designated this land for border security in 1907.

The buffer could extend from New Mexico to California, with officials considering its expansion westward if deemed successful.

Unlike in Texas, where Gov. Greg Abbott has deployed National Guard troops to assist in detaining migrants, military involvement in border enforcement in New Mexico has been more limited.

The Defense Department has already transferred parts of this federal land to the Pentagon for border security efforts.

How would the military’s role at the border change?

The plan would expand the military’s role beyond surveillance and logistical support, allowing active-duty troops to temporarily hold migrants until Customs and Border Protection (CBP) agents take custody.

Officials are evaluating whether unauthorized crossings in the buffer zone could be classified as trespassing rather than standard immigration violations.

What legal challenges could the plan face?

Legal experts warned the plan could violate the Posse Comitatus Act.

While the Trump administration has previously relied on CBP and Immigration and Customs Enforcement (ICE) to process detainees, placing military personnel in direct contact with migrants could trigger legal scrutiny.

Critics argued that the plan could face legal challenges under the Posse Comitatus Act. Immigration rights groups have also raised concerns over the human rights implications of expanded military presence at the border.

What other military actions has Trump ordered at the border?

Since returning to office, Trump has expanded military involvement at the border. According to U.S. military officials, more than 10,000 active-duty service members are now engaged in border security efforts.

Earlier this month, the Pentagon established a joint task force at Fort Huachuca, Arizona, to oversee operations. It deployed 2,400 troops from the Army’s 4th Infantry Division, including units equipped with 20-ton armored Stryker combat vehicles.

Defense officials will evaluate whether these vehicles can effectively maneuver within the buffer zone.

Additionally, the Trump administration recently deployed the USS Gravely, a U.S. Navy destroyer, to patrol waters near the southern border. The vessel operates alongside U.S. Coast Guard units to enforce maritime border security, part of broader efforts to curb unauthorized migration and drug trafficking.

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What impact has Trump’s border policy had so far?

Illegal crossings have declined significantly since Trump returned to office.

CBP reported 28,654 crossings in February 2025, down from 124,522 in December 2024 under former President Joe Biden. Trump administration officials credited increased military presence and stricter enforcement for the drop.

Trump’s latest immigration directives include expanding deportation flights, increasing border security technology and proposing military detention sites for undocumented migrants.

His defense secretary, Pete Hegseth, has endorsed the aggressive approach, stating, “We have defended other places and other spaces. We will defend this line.”

The administration’s push for “100% operational control” remains a central priority, with officials continuing to evaluate legal, logistical and diplomatic challenges tied to militarizing immigration enforcement.