The Department of Homeland Security documents critiquing the response to a simulated anthrax attack on Super Bowl Sunday were marked "For Official Use Only" and "important for national security."
Recipients of the draft "after-action" reports were told to keep them locked up after business hours and to shred them prior to discarding. They were admonished not to share their contents with anyone who lacked "an operational need-to-know."
But security surrounding the December 2017 reports suffered an embarrassing breach:
A CNN employee discovered copies of them, along with other sensitive DHS material, in the seat-back pocket of a commercial plane. The reports were accompanied by the travel itinerary and boarding pass of the government scientist in charge of BioWatch, the DHS program that conducted the anthrax drills in preparation for Super Bowl LII in Minneapolis.
This "government scientist" has not leaked what would normally be referred to as classified information in the broader sense. Documents marked For Official Use Only are sensitive, but not overly so. This is more a matter of mishandling sensitive information. It's not a complete and utter disaster, but it's terrible from a public relations point of view.
Reviewing these documents should have been done is a more controlled environment. I would think that someone will punish this person and restrict their access to sensitive materials until they can be retrained in the proper handling of this stuff.
If you're going to get into this line of work, expect to be held accountable.