The serious leak of classified and secret Pentagon documents on US activities in Russia and Ukraine, as well as the surveillance of officials, has caused a global uproar.

The Pentagon sees a “very serious risk” to US national security, and the Justice Department has launched a criminal investigation into the matter.

Read in detail: Pentagon leak: What do the classified documents that leaked online contain

In an article, the Washington Post reveals that the person who leaked the classified US intelligence documents is a 20-year-old man nicknamed OG (slang for ‘Original Gangster’) who worked at a military base and therefore the leak came from ” insider”.

The paper cites friends and colleagues of the 20-year-old with whom they chatted on the instant messaging platform Discord, in a group that shared a “love of guns, military equipment and God”.

It was on this platform that the classified documents and photos were first “uploaded” and the material was then circulated on platforms such as Twitter, 4chan and Telegram

The 20-year-old is said to be pro-gun, “fit and strong – “He’s trained. Pretty much everything you’d expect from a crazy movie,” said a member of the WP chat group.