As the U.S. government reels from a major leak of classified documents onto online networks and chatrooms, officials are offering few details about how the information -- much of it relating to Ukrainian aid -- got loose or if more is yet to come.
While the immediate government response has focused on trying to manage the fallout from the leaks -- including rebutting what appear to be doctored versions of documents -- officials are already acknowledging they will take a hard look at who has access to classified intelligence documents.
The Pentagon said Monday it is considering scaling back the number of personnel who receive sensitive classified material after it launched an interagency effort to review the reach of the document leak.
"We're still investigating how this happened, as well as the scope of the issue," Chris Meagher, a Pentagon spokesman, said in a briefing to reporters Monday. "There have been steps to take a closer look at how this type of information is distributed and to whom."
The leak represents a "very serious risk" to U.S. national security, Meagher said.
According to an April 2020 report, the U.S. granted "Top Secret" clearances -- the highest level possible -- to more than 1.3 million people. Another 2.7 million had access to lower, "Secret" and "Confidential" information.
That wide circulation of classified material is likely to complicate a review that is being led by Pentagon officials with the help of the National Security Council, State Department and Office of the Director of National Intelligence into the most recent leak.
John Kirby, the spokesman for the National Security Council, said that the White House does not know whether the leak has been contained.
"We don't know. We truly don't know," Kirby told reporters Monday.
While noting the Pentagon is already looking at whether to limit distribution of sensitive information, Kirby also said a pending Justice Department investigation should play out before the administration makes major policy changes.
Defense Secretary Lloyd Austin was first briefed on the leaked documents Thursday and by Friday began getting daily updates, Meagher said. Kirby said that President Joe Biden was also briefed "late last week."
The Pentagon and White House spokesmen both noted that at least some of the documents were doctored, and Kirby added that "there's just no way I can tell you, with any granularity right now, how that came to be."
As a result, Kirby said that officials "cannot speak to the veracity and the validity of any of those documents at this point."
The leaked documents likely had distribution across the Pentagon, as well as outside the department, and appear to be briefing materials for senior leaders on Ukraine- and Russia-related operations and other intelligence updates, Meagher said.
"These are documents that are used by a variety of people and departments within the Department of Defense to inform their work, and beyond the Department of Defense, frankly, to inform their work, and to provide intelligence updates to help us do our jobs," he added.
Finding leakers can be exceedingly difficult for documents that are widely distributed.
The man responsible for the largest leak of classified information in U.S. history, Edward Snowden, identified himself. The move led to immediate indictments as well as his flight to Ecuador, which was cut short when officials canceled his passport while he was on a layover in Russia.
By contrast, Reality Winner, a contractor and former airman who was charged with leaking a report on Russian hacking efforts connected with the 2016 election to The Intercept, was identified partly because she was one of only six people to recently print that particular report.
The Intercept also played a role in giving the government a lead into finding Winner.
Yet in the case of the latest leaks it appears that the documents may have been floating around the internet for weeks, if not longer, before being noticed by the media or the government. Investigative outlet Bellingcat reported that the documents have been floating around Discord -- a messaging platform popular with gamers -- since at least early March.
"We just need to be careful right now speculating or guessing what might be behind or who might be behind what looks like a potential leak here of classified information," Kirby noted.
Lawmakers, who are on a break from legislating in D.C. as part of a two-week congressional recess, have so far offered a muted response to the most recent leak. But some have expressed concern and expect to be briefed in the coming days.
"Any breach of classified material is serious, especially when sources and methods are identified," House Foreign Affairs Committee Chairman Mike McCaul, R-Texas, said in a written statement Monday. "I urge the administration to investigate and move swiftly to identify the leaker and take appropriate action. The administration must also brief Congress on the security implications of this leak."
Senate Armed Services Committee Chairman Jack Reed, D-R.I., is also "tracking this issue closely," a committee spokesperson said in an emailed statement.
Reed "believes that breaches of U.S. national security and intelligence must always be addressed with the utmost seriousness and urgency," the spokesperson added. "The Department of Defense and other agencies have launched investigations, and the Senate Armed Service Committee expects to be fully briefed on the Pentagon's investigation as it proceeds."
-- Konstantin Toropin can be reached at email@example.com. Follow him on Twitter @ktoropin.