The Pentagon, the Department of Justice and the greater world of Western intelligence is still reeling after it was revealed classified U.S. military documents appeared online. During the week of April 9,, a former Pentagon official said the source of the U.S. document leak could be an American.

Classified Pentagon documents revealing sensitive information about US/NATO plans for the proxy war in Ukraine have leaked.

The documents show that there are allegedly 50 British and 14 US soldiers in Ukraine. pic.twitter.com/mcMlfqWVZF

— MintPress News (@MintPressNews) April 7, 2023

Most of the world didn’t know about the documents until early April, but the Wall Street Journal reported the posts started showing up online in January. They initially appeared in a small chatroom on the social media platform Discord. The platform is mostly used by people who play video games to talk about gaming. The posts were eventually shared in different chat rooms and then wound up on Twitter and Telegram before being taken down.

The posts contained pictures of dozens of documents, including maps, pictures, and intelligence roundups apparently from the CIA. Some of the documents were dated from January and February, meaning they could have contained actionable intelligence. Many were marked classified or top secret. The information contained on the documents ranged from Ukraine’s air defense to Israel’s Mossad spy agency. Some documents even talked about the U.S. assessment of where and how Ukrainian troops should deploy for its much-anticipated spring counter-offensive.

Aside from Ukraine, the documents appeared to show the U.S. was spying on two of its other allies, Israel, and South Korea. The documents reportedly show the U.S. learned the Mossad was encouraging protests against Israeli Prime Minister Benjamin Netanyahu. In another document, the U.S. apparently gathered intelligence on the internal debate in South Korea of whether it should supply Ukraine with 155 mm artillery rounds.

U.S. intelligence officials said because of the breadth of topics covered, and the fact many of the documents were only in U.S. hands, the source of the leaks could be an American.

🔴 A Russian fighter jet nearly brought down a British surveillance plane last September with a leaked Pentagon document suggesting the incident was more serious than admitted by Defence Secretary, Ben Wallace.

Read more:https://t.co/4fMbHNGQW6 pic.twitter.com/0cXybxDNMp

— The Telegraph (@Telegraph) April 10, 2023

The FBI and the DOJ are investigating the leaks, which are being called the most wide-ranging and damaging to U.S. intelligence in years. If an American is indeed the source of the leak, it’s likely they would face treason charges. The possibility pro-Russian elements are behind the leaks to possibly sow disinformation, however, is not being ruled out.

Some of the information on the leaked pictures appeared to have been doctored, poorly. One document said only around 43,000 Russian troops had been killed or wounded since fighting began. Western intelligence agencies said the actual number is closer to 200,000.

Other information could still be credible, though, and coincides with what was taking place at the time the pictures were reportedly taken. For instance, the claim Ukraine could run out of air defense missiles by May, which would be another reason it was and is lobbying so hard for Western fighter jets like the F-16.

While it is still unknown who released the documents or why, the impact of their release is undeniable. One senior Western intelligence official called the leak a “nightmare” because the Kremlin could use the documents to figure out how the West was spying on Russian troop movements. The documents could also be used as a wedge between the U.S. and its allies. Ukraine is also being forced to now alter some aspects of its counter-offensive plan as well.

In addition to investigating the leaks, the Pentagon said it also made changes to how it distributes classified information and will look to limit who is granted access to certain documents moving forward.

Reuters contributed to this report.