The United States has been spying on UN chief Antonio Guterres since it considered the way he dealt with Russia was too lenient, the leaked classified Pentagon documents revealed.

Commenting on the leak, Guterres stated that he is not surprised about being spied on, a spokesperson for the United Nations Stephane Dujarric said on Thursday.

"The Secretary-General... has been in politics and a public figure for quite some time," Dujarric told reporters. "So he is not surprised, I think, by the fact that people are spying on him and listening to his private conversations."

As early as March 2, 2023, over 100 intelligence papers were posted on Discord, a social media platform popular with gamers, and appeared to contain highly classified information - originating mainly from Pentagon - on Ukraine, Russian military activity, China, and the Middle East. 

The newly surfaced document concentrates on the Black Sea Grain Deal, which was brokered by the UN and Turkey between Russia and Ukraine in July 2022 and came in response to an imminent global food crisis then.

According to one of the documents, Guterres wanted to maintain the deal even if it meant going lean on sanctions against Moscow.

Read more: US allies going berserk over Pentagon intel leak: Politico

"Guterres emphasized his efforts to improve Russia's ability to export," one document said, "even if that involves sanctioned Russian entities or individuals".

His actions were “undermining broader efforts to hold Moscow accountable for its actions in Ukraine,” the leaked file revealed.

Another document dating back to February shows a closed conversation between the UN chief and his deputy, Amina Mohammed, where he sounded his “dismay” regarding the calls of European Commission President Ursula von der Leyen to increase arms production by the bloc's member states after the war in Ukraine.

The leak had left relations with allies in a state of crisis as the incident is reported to be the largest since Wikileaks exposed classified files from 2006 to 2021.

Read more: South Korea denies spying allegation in US leaked documents

Source?

According to newly-disclosed information, the source of the leaked US documents is a man in his early to mid-20s who works on a military post and is known for his critical views of the US government.

The Washington Post published an exclusive piece late Wednesday that presented a description of the guy behind the leaks and provided insight into how the disclosures came to be. The story was based mostly on the information given by a minor who met the leaker online four years ago in a Discord server for fans of the YouTuber Oxide.

WashPo was also given 300 photos of secret papers, chat records, and an audio recording of the source of the leaks chatting with his friends.

The leaker was apparently seen at a shooting range yelling racial and antisemitic comments before discharging his pistol in one footage reviewed by the website.

The adolescent told the magazine that the leaker, designated as 'OG', began making his own reports of the secret material and distributing the data in their own, smaller group chat for several months. 'OG' utilized the site to keep members "in the loop" about international events and government actions, according to the minor.

Images shared by 'OG' were inevitably passed on to another online community, unknown to the so-called 'tight-knit' group of pals. It was discovered that the materials had been shared by another adolescent.

Following the leak of US "top secret" documents, CBS News reported, on Wednesday, that the Pentagon significantly reduced the number of government-employed officials that receive classified information.