The e-mail scandal that has been plaguing Mrs Hillary Clinton's presidential campaign took a potentially damaging turn when the State Department declared 22 e-mail messages that passed through her private computer server "top secret".
The revelation marked the first time the State Department has found anything highly classified in the former secretary of state's correspondence, and it also now raises the possibility that Mrs Clinton's decision to use her own e-mail server while in government service might have resulted in a serious breach.
Coming just three days before the critical Iowa caucuses tomorrow, the issue threatens to further unsettle a Clinton campaign that is in a close fight with Senator Bernie Sanders. The possibility that former New York mayor Michael Bloomberg could join the race has also piled pressure on the Democratic Party front runner.
On Friday, as part of its ongoing, court-ordered release of Mrs Clin- ton's e-mail messages, the State Department said it would hold back 22 documents covering 37 pages.
"I can confirm that as part of this monthly FOIA (Freedom of Information Act) production of former secretary Clinton's e-mails, the State Department will be denying in full seven e-mail chains found in 22 documents, representing 37 pages," department spokesman John Kirby told a briefing.
"The documents are being upgraded at the request of the intelligence community because they contain a category of top secret information."
It was not immediately clear if the messages in question were sent by Mrs Clinton or received by her.
Similarly, when asked directly if rules were broken, Mr Kirby would only say: "The State Department is going to take a look here at that. I'm not in a position today to say definitively one way or the other."
Still, the Clinton campaign on Friday pushed back hard on insinuations that the former state secretary might have failed to protect highly classified information, stressing the messages were not marked as classified at the time they were sent.
"We understand that these e-mails likely originated on the State Department's unclassified system before they were ever shared with secretary Clinton, and they have remained on the depart- ment's unclassified system for years," Mrs Clinton's press secretary Brian Fallon said.
"This appears to be over-classification run amok. We will pursue all appropriate avenues to see that her e-mails are released in a manner consistent with her call last year," he added, referring to her remarks last year calling on the State Department to make public all her messages.
Mrs Clinton has always maintained that she broke no law and was simply using her own e-mail server out of convenience. US law requires all work-related e-mail from government employees as public records without specifying that official e-mail accounts be used.
Thus far, it remains unclear if and how much the revelation would hurt her chances in Iowa. Despite much attention from the news media and her Republican opponents when the e-mail issue first came to light last March, it has failed to catch fire among ordinary voters.
On Friday, Republican candidates were quick to pounce on the announcement, saying it was a clear sign of her lack of judgment.
"Hillary Clinton is a major national security risk. Not presidential material!" tweeted business mogul Donald Trump.
