The Pentagon has given the Department of Homeland Security permission to test a military-grade heat ray and develop tactics for its potential use along the southern US border, according to a memorandum signed by Defense Secretary Pete Hegseth and first obtained by CNN, which reported the story on October 21, 2026. Deploying the weapon — officially known as the Active Denial System — at the border would be an unprecedented step, raising new questions about the line between military technology and civilian immigration enforcement.
Secretary of Defense Pete Hegseth, who signed the memorandum authorizing DHS to test the Active Denial System. (U.S. Department of Defense photo)
The Memo: Seven Months, One System
The memorandum, which Hegseth signed last month, authorizes the "temporary loan" of one Active Denial System to DHS for seven months, starting in September. Under the arrangement, DHS becomes solely responsible for "system employment, use and development of tactics, techniques and procedures," and the weapon "shall not be operated by DoW (Department of War) personnel."
That language, according to CNN's reporting, appears to absolve the Pentagon of responsibility for how the directed-energy system may ultimately be deployed. At the end of the seven-month period, DHS can submit an additional request for continued use of the system in border operations, a defense official told CNN.
The authorization covers testing and the development of tactics — not operational deployment. The DHS request did not specify where or how the weapon would be tested, nor how it might eventually be used. Customs and Border Protection told CNN it is "continually evaluating new technologies, especially those that enhance operational effectiveness and strengthen mission capabilities." The Pentagon referred CNN to DHS when asked for comment.
Even so, the move breaks new ground. Over the years, current and former Customs and Border Protection officials have described internal discussions about potentially using the system for crowd dispersal along the US-Mexico border — but it has never actually been deployed there.
A vehicle-mounted Active Denial System during a U.S. military demonstration. The Pentagon has authorized a seven-month loan of one such system to DHS. (U.S. military photo)
How the Weapon Works
The Active Denial System is a nonlethal directed-energy weapon that fires an invisible beam of electromagnetic waves capable of reaching a little more than half a mile away, according to the US military.
When the beam strikes human skin, it produces an intense burning sensation. Pentagon officials have previously compared the feeling to the blast of heat a person feels when opening a hot oven. Military officials have said the resulting "tingling effect" lasts between 10 and 15 minutes and also generates "an instinctive and irresistible urge to run from the effect."
Unlike conventional firearms, the system is designed to repel or disperse people without firing a projectile. Its effects are intended to stop the moment a person moves out of the beam's path. The military developed the technology for crowd-control purposes, and it is formally classified as non-lethal — though experts and officials have long debated what that label actually guarantees in real-world conditions.
A Long, Troubled History
This is far from the first time US officials have considered pointing the heat ray at people. The system was briefly shipped to Afghanistan nearly two decades ago, but the US military ultimately declined to use it during active combat operations.
American officials also considered the system for crowd control at US facilities abroad where terrorist detainees were being held — and declined to employ it there as well, according to a source familiar with those internal considerations.
Domestically, the idea keeps resurfacing. US officials considered deploying the system during moments of domestic unrest, including at the end of President Donald Trump's first term when protests erupted over the murder of George Floyd, according to a former US official familiar with those discussions.
In 2018, in the run-up to the midterm elections, Customs and Border Protection officials weighed using the system against migrants — but then-Homeland Security Secretary Kirstjen Nielsen shot the proposal down. "The issue was treating immigrants and citizens like enemy combatants," a former DHS official familiar with the discussions told CNN. "Thematically, inhumane treatments typically get rejected."
More recently, officials in the El Centro sector — which covers about 70 miles of the US-Mexico border — evaluated the system several years ago, when Rodney Scott, who now serves as CBP commissioner, was leading that sector, according to a CBP official. Agents discussed whether it might help with surges of illegal crossings along the nearby river, either by discouraging people from attempting crossings or by pushing them out of the water. It was never deployed, and the precise reasons remain unclear.
The U.S.-Mexico border wall. Deploying the heat ray at the southern border would be unprecedented, according to CNN's reporting. (File photo)
Why Officials Keep Hesitating
Behind the scenes, officials have repeatedly run into the same set of concerns: legalities, the use-of-force questions, basic effectiveness — and the risk that people could be harmed, directly or indirectly, by a weapon advertised as nonlethal.
Sovereignty adds another layer. A beam fired from American territory could strike people still on the Mexican side of the border, raising questions about whether using the system on people who have not yet crossed into the United States would violate international norms.
Then there is the practical, human worry. "Even if they're chasing people back to the river, you don't want them to go in and drown," a former CBP official told CNN. "For the cost, for the training and for the policies you're going to create, is the juice worth the squeeze?"
That cost-benefit calculation has only gotten harder for supporters of the idea. Some Border Patrol agents have recently cast doubt on whether they even need the tool, given that border crossings are low and personnel numbers have increased, according to another former CBP official.
What This Means
The seven-month loan does not mean a heat ray is about to sweep migrants off the border — it means DHS now has the time, the hardware, and the Pentagon's formal permission to figure out whether it could. That distinction matters, but so does the signal it sends.
For an administration that has made border security and cracking down on immigration top priorities, the Active Denial System represents a new frontier in enforcement technology: a weapon that inflicts intense pain without bullets, controllable at the press of a button, effective at half a mile. Supporters see a tool that can move crowds without lethal force. Critics see a military weapon being repurposed for civilian enforcement against people whose "crime" is crossing a border.
The memo's careful legal framing — the loan is "temporary," Pentagon personnel will not operate it, DHS owns all responsibility — shows the administration knows how sensitive this is. It also places a crowd-control technology built for the battlefield under the authority of a department responsible for civilian border enforcement, a shift with few real precedents.
What Happens Next
DHS has roughly seven months from September to evaluate the system and develop operating procedures. Whether testing turns into a request for operational use — and whether such a request would survive the legal, diplomatic, and political scrutiny that sank every previous attempt — remains to be seen.
Watch for three things. First, whether DHS discloses where and how it tests the system; the original request specified neither. Second, whether the El Centro-style questions about river crossings, rescues, and sovereignty produce written rules of engagement. Third, whether lawmakers or courts weigh in — the same concerns that stopped Nielsen in 2018 and military commanders in Afghanistan have not gone away, and the beam is no less painful than it was then.
For now, the heat ray sits in federal hands, untested at the border. The seven-month clock is already running.
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