Washington: US authorities on Thursday arrested a suspect in the case of leaked classified documents, according to US media, which has honed in on a young National Guard member as the possible source of the security breach.
The FBI made a "probable cause" arrest of a man identified by authorities as a member of the Massachusetts Air National Guard, ABC News reported.
CNN aired footage from North Dighton, Massachusetts showing the detainee in shorts with his hands behind his back and being placed by agents into an unmarked vehicle.
US President Joe Biden earlier on Thursday said investigators were closing in on the source of the leak in what is believed to be the most serious security breach in years.
Separately, the New York Times reported that the leader of an online group where the secret documents were posted is a member of the Massachusetts Air National Guard.
It named him as Jack Teixeira, a National Guardsman who led Thug Shaker Central, an online group where about 20 to 30 people shared their love of guns, racist memes and video games. The Times cited interviews and documents it reviewed. Reuters could not immediately confirm the guardsman's identity.
The US Department of Justice opened a formal criminal probe last week after the matter was referred by the Pentagon, which is assessing the damage.
Reuters has reviewed more than 50 of the documents, labeled "Secret" and "Top Secret" but has not independently verified their authenticity. The number of documents leaked is likely to be over 100.
Biden, on a three-day tour of Ireland, said he was not overly concerned about the leak.
"There's a full-blown investigation going on, as you know, with the intelligence community and the Justice Department, and they're getting close but I don't have an answer," Biden told reporters.
"I'm not concerned about the leak, I'm concerned that it happened but there is nothing contemporaneous that I'm aware of." The FBI Washington field office is leading the investigation, according to a person familiar with the matter.
A man with the same name as that mentioned by the New York Times, Jack Teixeira, was promoted to Airman 1st Class last July, according to a post on the 102nd Intelligence Wing's official Facebook page. The unit did not immediately return an email seeking comment.
A number of countries have questioned the veracity of some of the leaked documents, including Britain, which said there was "a serious level of inaccuracy" in the information.
The person who leaked the documents is a gun enthusiast in his 20s who worked on a military base, the Washington Post reported on Wednesday, citing members of an online chat group.
Source of leak
The Post based its report, which did not name the person, on interviews with two members of the Discord chat group. Discord said in a statement that it was cooperating with law enforcement.
Reuters was unable to verify details of the report. Its broad outlines - that the documents were first shared on a Discord server for gun and ammo enthusiasts who often swapped offensive jokes - were initially reported by Netherlands-based investigative journalism group Bellingcat last week.
Since the leak first came to light in March, investigators have been pursuing theories ranging from someone simply sharing the documents to show off the work they were doing to a mole inside the U.S. intelligence community or military.
The leaks have drawn responses from foreign partners of the United States.