Pentagon clears Homeland Security tests of military heat ray for US southern border

A memo authorizes the test

The Pentagon has allowed the Department of Homeland Security (DHS) to test the Active Denial System, a military-grade weapon that fires an invisible beam of electromagnetic energy and causes a burning sensation on human skin. CNN obtained the memo, which Defense Secretary Pete Hegseth signed in September, and it approves a seven-month loan of the system starting that month. The Pentagon will provide the equipment but will not operate it, and the memo places sole responsibility for using the system and developing its tactics, techniques and procedures with DHS. The document does not say where or how the weapon would be tested, or how it might be used at the border. Approval does not mean deployment, and it remains unclear whether DHS will ultimately use the system.

How the beam works

The weapon reaches just over half a mile, about 1 km, according to the military, while Axios puts the range at up to 1,000 meters. Officials compare the sensation to the blast of heat felt when opening a hot oven, and they say it triggers an almost instant reflex to flee. The burning stops once a person leaves the beam, but tingling or tenderness can remain for 10 to 15 minutes. The Pentagon says the device was designed to be nonlethal, and that killing someone would require exposure lasting many times longer than what is needed to repel them.

Injuries and earlier plans

Axios reports at least two documented cases of second-degree burns: a 1999 laboratory accident that left one person with a blister, and a 2007 training exercise in which an airman was overexposed after procedural errors. Border officials have discussed internally using the system to disperse crowds along the southern border, but it has never been used there. A 2018 plan to use it at the border was reportedly halted under then-Homeland Security Secretary Kirstjen Nielsen. The system was taken to Afghanistan by the US military in 2010 but never used. Officials also considered it during domestic unrest, including after the killing of George Floyd in 2020, according to former officials cited by CNN.

A Customs and Border Protection spokesperson responded to Axios with a statement on the testing:

CBP is continually evaluating new technology, especially technology that can save lives while simultaneously enhancing national security effectiveness.

Legal and safety questions

Border officials have raised doubts about the legality and potential harm of the system. A former CBP official told CNN that even when people are being pushed back toward a river, officials should not let them go in and drown, and questioned whether the cost, training and new policies were justified. Legal questions would be especially sensitive if the beam were aimed at people on Mexican territory. Hegseth's deputy chief of staff, Patrick Weaver, wrote about the testing in an X post:

The border is now a military installation and a battle lab for testing new systems, to include directed energy weapons.

What comes next

The memo leaves the test sites and methods open, and DHS alone will set the rules for any future use. The timeline below places the system's earlier history alongside the memo and the October reporting.