The worst Pentagon leak in years may have started in a gamer chatroom, where people weirdly keep posting classified documents trying to win arguments on the internet

• The leaked Pentagon documents may have started in an online chatroom for gamers.
• An investigation into the origin revealed they were shared during an argument over Ukraine.

Secret documents containing US intelligence appear to have been first posted to a gamer forum in what has become the worst Pentagon leak in years, but it's not the first time highly sensitive and classified documents have ended up in these kinds of chatrooms.

The trove of documents containing highly sensitive military and security information about US allies and adversaries recently circulated on social media platforms and are now the focus of a federal investigation.

It is still not immediately clear who leaked the dozens of documents and when they did, but many of the documents appear to be from late February or early March. Within the first few days of March, at least a few documents were posted to a Discord server dedicated to the "Minecraft" video game, according to a Bellingcat investigation. Discord is a messaging platform where users can send photographs, videos, audio, and text to various chatrooms.

In one chat server called "Minecraft Earth Map," users appeared to get into an argument about Russia's war in Ukraine, and one apparently posted the sensitive documents in an attempt to win the debate, Bellingcat found. "Here, have some leaked documents," the user wrote in response to the discussion.

The Department of Justice, which has opened a criminal investigation into the troubling leak, declined to comment on a query from Insider about their origin online.

If the leaks are officially found to have originated in a gamer chatroom, it will not be the first instance where users trying to win arguments online have gone so far as to disclose classified documents in one of these forums. In recent years, players of "War Thunder" — a combat video game — have shared highly sensitive information to various chatrooms on multiple occasions, including content about tanks, fighter jets, and missiles.

In one case, a user posted information from the manual of an F-16 fighter jet, as well as content about the AIM-120 Advanced Medium-Range Air-to-Air Missile. According to Popular Mechanics, this came shortly after a member on a forum disclosed information about the F-15E Strike Eagle fighter jet.

Other examples include users sharing information about France's Leclerc main battle tank during an argument between users, according to the UK Defence Journal. The same outlet reported that classified information related to Britain's Challenger 2 tanks was also posted in a discussion about the weapon's accuracy in the game.

Unlike whistleblower actions or spycraft, these leaks of sensitive information online appear — at least in some cases — to be about proving a point and simply being right on the internet. The most recent leaks, which some experts say is the most significant intelligence breach in decades, could have tremendous and far-reaching implications.

The trove of documents contains highly sensitive military information about US allies and partners — like Israel, South Korea, and Egypt — and adversaries like Russia, China, and Iran.

A large portion of the documents appear to focus on the war in Ukraine and include information such as detailed maps, force attrition rates, weapons assessments, and combat readiness. One document in particular outlines how many casualties both sides have suffered, while a different assessment reviews Ukraine's past battlefield preparations. Another document highlights concerns about a US-made bomb kit that's been sent to Kyiv.

The disclosure has triggered panic in Washington and in the capitals of its partner countries, some of which have pushed back against the claims made in the documents, and has US officials scrambling to probe how the documents were leaked and circulated.

A senior Pentagon official said Monday that the Pentagon is still investigating and that this is "a top priority" for the Department of Defense.

"We take this very seriously," Defense Secretary Lloyd Austin told reporters on Tuesday. "And we will continue to work closely with our outstanding allies and partners, and nothing will ever stop us from keeping America secure."