For technology users who have marveled at the ability of Siri or Alexa to recognize their voice, consider this: The National Security Agency has apparently been way ahead of Apple or Amazon.

The agency has at its disposal voice recognition technology that it employs to identify terrorists, government spies, or anyone they choose — with just a phone call, according to a report by The Intercept. The disclosure was revealed in a recently published article, part of a trove of documents leaked by former NSA contractor Edward Snowden.

The publication wrote that by using recorded audio, the NSA is able to create a “voiceprint,” or a map of qualities that mark a voice as singular, and identify the person speaking. The documents also suggest the agency is continuously improving its speech recognition capabilities, the publication noted.

According to a classified memo obtained by The Intercept, the agency has employed this technology since at least 2006, with the document referencing technology “that identifies people by the sound of their voices.”

In fact, the NSA used such technology during Operation Iraqi Freedom, when analysts were able to verify audio thought to be of Saddam Hussein speaking. It suggests that national security operatives had access to high-level voice technology long before Amazon, Apple and Google’s solutions became cultural touchstones.

A “voiceprint” is “a dynamic computer model of the individual’s vocal characteristics,” the publication explained, created by an algorithm analyzing features like pitch and mouth shape. Then, using the NSA’s formidable bank of recorded audio files, the agency is able to match the speaker to an identity.

Identifying people through their voiceprints is a skill at which the “NSA reigns supreme,” according to a leaked document from 2008. And, they’re only getting better.

The NSA did not immediately reply to CNBC’s request for comment. The full story can be found on The Intercept’s website.