One reason given for the Trump administration to not notify Congress, or even the gang of eight, in advance about recent military attacks is fear of leaks. Has the gang of eight or similar congressional leadership ever leaked information about upcoming military action?
The Gang or Eight specifically relates to intelligence matters, as the National Security Act it 1947 (which has been amended though the years) requires that intelligence agencies keep Congress “fully and currently informed” on intelligence matters. In cases of particular sensitive intelligence, a handshake agreement has been made that notifying the leaders of each house and the chair and rankings of the two intelligence committees is sufficient under the circumstances.
The Gang or Eight is not a catch-all for any sensitive information relating to national security writ large. The intel committee chairmen have no oversight over troop movements or military strikes, for example.
The leaders and the defense committee chairmen have usually been given some advance notice of important military operations, but that is also just a gentlemen’s agreement and not always followed. (See the furor over the Baghdadi raid.)
I’m not aware of any specific assertions that any of these members have leaked something critical in the spirt the OP was talking about. (There’s a few edge cases I know of, like when in August 2016, Harry Reid called for an FBI investigation into Russian election interference, when he as a member of the Gang of Eight surely knew exactly what was going on.)
Of course, Congress in general leaks all the time, and the Pentagon and the White House (all of them, not just this one) leak even more. I mean, how do you think reporters get stories out on military operations so quickly after they happen?
Thank you.
The more general question then becomes: Has a member of Congress, having been briefed on upcoming military action, leaked the info prior to the event?
After the event is a different situation.
Not to my knowledge.
This is not exactly that, but a leak about specific details of an on-going military activity:
Andrew Jackson May (D Kentucky), “chairman of the House Military Affairs Committee during World War II, infamous for his rash disclosure of classified naval information that resulted in the loss of 10 American submarines and 800 sailors”
Wikipedia article: Andrew J. May See section on the May Incident.
Fast food outlets get paid to tell reporters when large quantities of food are ordered