The NYPD have deployed military-grade top secret X-ray vans throughout the city, enabling officers to look through walls of buildings and vehicles.

The $800,000 vans have been rolled out across New York City, but the NYPD are currently refusing to say what their purpose is.

“I will not talk about anything at all about this,” New York Police Commissioner Bill Bratton said when asked what the Backscatter Vans were being used for. “It falls into the range of security and counter-terrorism activity that we engage in.”

Nypost.com reports:

“They’re not used to scan people for weapons,” Bratton insisted. “The devices we have, the vehicles if you will, are all used lawfully and if the ACLU and others don’t think that’s the case, we’ll see them in court — where they’ll lose! At this time and the nature of what’s going on in the world, that concern of theirs is unfounded.”

He declined to give more specific details about the devices themselves.

“Those are issues I’d prefer not to divulge to the public at this time,” Bratton said. “I will not talk about anything at all about this — it falls into the range of security and counter-terrorism activity that we engage in.”

The website ProPublica filed suit against the NYPD three years ago after an investigative journalist’s requests for police reports, training materials and health tests related to the X-rays were denied.

New York State Supreme Court Judge Doris Ling-Cohan ruled that the department should have to turn over the records, despite the NYPD’s arguments that disclosing that information could interfere with investigations.

“While this court is cognizant and sensitive to concerns about terrorism, being located less than a mile from the 9/11 site, and having seen firsthand the effects of terrorist destruction, nonetheless, the hallmark of our great nation is that it is a democracy, with a transparent government,” the judge wrote in the December 2014 decision.

The NYPD appealed that decision — and now the NYCLU has requested to file an amicus brief urging the appeals court to uphold the lower court’s original ruling.

“People should be informed if military-grade X-ray vans are damaging their health with radiation or peering inside their homes or cars,” said NYCLU Executive Director Donna Lieberman. “New Yorkers have a right to protect their health, welfare and privacy.”

Little is known about how the NYPD uses the high-tech machines, which reportedly cost between $729,000 and $825,000.

The vans are also employed by US Customs and Border Protection to scan for drugs and explosives.