Secretary of State John Kerry’s testimony in front of the Senate Foreign Relations Committee on Tuesday produced a number of revelations about the ongoing Hillary Clinton email probe, including that she was provided an email account during her time at the agency designed to handle classified information but never used it.

During one part of an at-times intense exchange, Wisconsin Sen. [crscore]Ron Johnson[/crscore] read from a letter from Julia Frifield, who serves as State Department assistant secretary of state for legislative affairs.

“Secretary Clinton did not use a classified email account at the State Department. An account was set up on ClassNet on her calendar, but it was not used,” Frifield wrote in response to a Sept. 21, 2015 letter from the committee asking for information about Clinton’s use of an account equipped to handle classified information.

ClassNet refers to the State Department workstations that are designed to allow employees to view classified information.

But while Clinton did not consume classified information in that system, she did so on her own personal email account, which was hosted on a private server that was housed at her residence.

More than 1,700 of Clinton’s work-related emails have been retroactively determined to contain classified information. Of those, approximately two dozen contain “Top Secret” information. And information in at least two of those was classified at the time the emails were sent, the Intelligence Community’s inspector general has determined.

Clinton’s server was seized by the FBI, which is investigating whether classified information was mishandled.

It is unclear why Clinton did not use the classified account that was created for her.

But the Democratic presidential candidate has insisted that she did nothing wrong by opting instead to use a personal email account and private server. She claims that none of the classified information contained on the server was “marked” as such when it was originated. She has disregarded those who have pointed out that she signed a non-disclosure agreement acknowledging that classified information is classified whether it is marked or unmarked.

Clinton’s website addresses the question of how she consumed classified information. It reads:

The Secretary’s office was located in a secure area. Classified information was viewed in hard copy by Clinton while in the office. While on travel, the State Department had rigorous protocols for her and traveling staff to receive and transmit information of all types. A separate, closed email system was used by the State Department for the purpose of handling classified communications, which was designed to prevent such information from being transmitted anywhere other than within that system.

Kerry provided other insight into the ongoing investigations into Clinton’s email habits.

[dcquiz] Asked at one point by Johnson whether he knows if the intelligence community has had to “mitigate the harm by the potential that our enemies might have access to that classified material that’s on Secretary Clinton’s server,” Kerry demurred.

“I would not be able to discuss that in an open session,” he said.

And when pressed by Johnson whether Kerry would use or allow his staff to use a private server to send and receive classified information, Kerry admitted, with some hesitation, that he would not.

“In today’s world, given all that we’ve learned and what we understand about the vulnerability of our system, we don’t do that, no,” Kerry said.

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