The US military mistakenly shot down a Customs and Border Protection (CBP) drone near the Mexican border in a strike that reportedly used a laser-based anti-drone system. The CBP uses drones to track people crossing the border.

“Congressional aides told Reuters the Pentagon used the high-energy laser system to shoot down a Customs and Border Protection drone near the Mexican border, in an area that often has incursions from Mexican drones used by drug cartels,” Reuters reported last night.

The FAA closed some airspace along the border with Mexico in Fort Hancock, Texas, on Thursday with a notice announcing temporary flight restrictions for special security reasons. The restrictions are in place until June 24 but could be lifted earlier. There are conflicting reports on which day the strike happened, with The New York Times reporting that the strike occurred Thursday and Bloomberg writing that the Federal Aviation Administration (FAA) “was notified Wednesday after the event occurred.”

“The Defense Department didn’t realize the drone was being flown by CBP when it shot it down,” and “had not first coordinated the use of the laser system with the US Federal Aviation Administration,” Bloomberg wrote, citing anonymous sources.

The military hasn’t been coordinating counter-drone measures with the FAA, and “CBP drone operators didn’t inform the military’s laser unit that it was launching,” Bloomberg wrote, citing anonymous sources. Because the CBP didn’t notify the Defense Department, the military viewed the aircraft as “an unknown drone,” the Times wrote, citing an unnamed Pentagon official.

Two laser strikes in February

The latest incident came about two weeks after the FAA abruptly closed airspace over El Paso for a few hours, leading to flight cancellations. In the early February incident, CBP was the one that fired the laser. The CBP was “using the same technology on loan from the military to combat drug-smuggling” and “fired a high-energy laser at what they thought was a drone,” but turned out to be a party balloon, the Times wrote.

“In both cases, the lasers were used without the FAA’s approval, which many aviation safety experts maintain is a violation of the law,” the Times wrote.

Democratic lawmakers criticized the Trump administration. “The Trump administration’s incompetence continues to cause chaos in our skies,” Sen. Tammy Duckworth (D-Ill.), ranking member of the Senate Aviation Subcommittee, said in a statement provided to Ars. Duckworth said, “The situation is alarming and demands a thorough, independent investigation.”