A it depends on what the meaning of “is” is defense?
As strange as it sounds, this actually came up early in 2017 when the new Trump administration was dealing with all kinds of leaks to the media. A lawyer on a news show -- maybe on Fox News -- was asked what legal jeopardy someone would be in for leaking the contents of conversations in the White House to reporters. His answer caught me by surprise but it seems obvious when you think about it. He said something to this effect: "There's no legal basis to charge someone for leaking allegedly classified information if the information they 'leak' is not true."