If true, the latest revelation about Hillary Clinton’s secret e-mail system goes way beyond “smoking gun.” It reaches the level of full core meltdown when it comes to US national security and the safety of American intel sources. Fox News reporters Catherine Herridge report that the Inspector General has noted that information in one or more e-mails contained information classified as “HCS-O,” denoting extraordinarily sensitive material that could put a human intel source at high risk if exposed:

At least one of the emails on Hillary Clinton’s private server contained extremely sensitive information identified by an intelligence agency as “HCS-O,” which is the code used for reporting on human intelligence sources in ongoing operations, according to two sources not authorized to speak on the record.

Both sources are familiar with the intelligence community inspector general’s January 14 letter to Congress, advising the Oversight committees that intelligence beyond Top Secret — known as Special Access Program (SAP) — was identified in the Clinton emails, as well the supporting documents from the affected agencies that owned the information and have final say on classification.

According to a December 2013 policy document released by the Office of the Director of National Intelligence: “The HSC-0 compartment (Operations) is used to protect exceptionally fragile and unique IC (intelligence community) clandestine HUMINT operations and methods that are not intended for dissemination outside of the originating agency.”

It is not publicly known whether the information contained in the Clinton emails also revealed who the human source was, their nationality or affiliation.

According to the Authorized Classification and Control Markings Register, the HCS classification applies to human intelligence (HUMINT) that is also classified at the SCI level — Sensitive Compartmented Information. The SCI classification is itself another form of higher classification; we first saw this come up in the context of Hillary’s e-mail system last summer, when Top Secret/Compartmented data from the National Geospatial-Intelligence Agency (NGA) and NSA showed up in her e-mails. That dealt with satellite data about North Korea’s nuclear program, and the exposure of that data could have allowed our enemies the ability to render our satellite data-collection capabilities useless.

If Hillary’s server transmitted and retained SCI/HCS in an unsecured and unauthorized manner, the US would be very lucky to still have that source available to us. This goes beyond gross negligence; it demonstrates an utter contempt not only for national security, but for the risks faced by those who gather intelligence and cooperate with the US to safeguard the country.

Herridge and Browne also report that IG Charles McCullough has briefed key members of Congress on just how much this was not just an “interagency dispute” over publicly discussed topics:

The source said that the “several dozen” refers to the main or principal email thread identified by reviewers, not the number of times that classified information was forwarded, replied to or copied to people who did not have a “need-to-know” using unsecured communication channels — in this case a personal server.  More than one Special Access Program was affected. …

The two declarations provided to the heads of the House and Senate Intelligence committees — as well as the leadership of Senate Foreign Affairs with oversight for the State Department — include the emails containing SAP intelligence, as well as supporting documents from the agency affected, showing how they reached the determination it came from one of its sources, and not from publicly available information.

The originators of this information would know precisely what came from sources in the clear, and which came from their most sensitive data. The question will be whether the FBI has also mapped out the manner in which this information got manipulated into unsecured systems so that the Secretary of State could hide her communications from Congress and the courts, and whether the Department of Justice will prosecute what might be the worst spillage outside of a purposeful espionage effort in recent memory, if not ever.

Update: Robert Gates told Hugh Hewitt yesterday that the “odds are pretty high” that Russia, China, and Iran had compromised Hillary’s home-brew server:

HH: One of your colleagues, Mike Morell, said on this program, or actually agreed with my assertion that almost certainly, Russians, Chinese and Iranians had compromised the home brew server of the former Secretary of State. He agreed with that. Do you agree with his assessment of my assessment?

RG: Well, given the fact that the Pentagon acknowledges that they get attacked about 100,000 times a day, I think the odds are pretty high.

HH: And so if they had real time access to her server, would that have compromised national security?

RG: Well, again, it would depend entirely on what she put on there. And I just, I haven’t read any of these emails, so I don’t know what was on those servers.

If it’s SCI and HSC information, then the clear answer is yes.