The NSA has a computer monitoring tool that uses a technology which allows it to access computers and modify their data, even when they aren’t connected to the internet, according to the New York Times.

Part of this program, known as Quantum, uses radio transmission technology to infiltrate hundreds of thousands of computers in countries outside of the U.S. While the spy agency primarily accesses computers through their connected networks, they are increasing use of the radio technology.

An agency catalog, part of documents released by former contractor Edward Snowden, contains many pages of the devices used by the NSA.

One such device, known as Cottonmouth 1, looks much like a regular USB cable. However, a radio transmitter is embedded into the connector, which transmits data from the computer and also lets the NSA install data via secret radio frequencies.

Other variants of this technology use mini circuit boards implanted in laptops, which are intercepted and installed when they are shipped from the manufacturer.

On the other end, a relay station known as a Nightstand can wirelessly install software exploits from up to eight miles away. These are the types of devices that allow the NSA to target computers that aren’t connected to the internet, or any network.

There currently isn’t any evidence showing this type of hardware or software has been installed on computers within the U.S. The NSA and United States Cyber Command have primarily focused the program at the Chinese army, Russian military, EU trade groups, Mexican police, and allies including Saudi Arabia, Pakistan, and India.

The program has given the U.S. a window it’s never had before.

James Andrew Lewis, cybersecurity expert of the Center for Strategic and International Studies, stated the NSA’s ability to infiltrate and install software onto systems via radio “has given the U.S. a window it’s never had before.”

In a statement published by The Economic Times, NSA officials did not directly comment on the New York Times’ story, however they did acknowledge their agency uses “various foreign intelligence techniques to help defend the nation.” Officials went on to say the techniques are used only against “valid foreign intelligence targets in response to intelligence requirements” and are not used to steal trade secrets from foreign companies.