It is becoming apparent that, as suspected, PFC Bradley Manning was the source for WikiLeaks' latest document dump of classified Afghanistan data. That information, if you were not already aware, includes descriptions of Afghan informants, to include name, father's name, and village. (Those three things combined are the closest thing you can get to name, phone number, address, and SSN for an Afghan, and really, are just as good.) Those people are now dead men. In the event that they're yet walking around, that is a condition the Taliban is actively taking steps to rectify at this very moment.
From a "big picture" perspective, the even greater harm is how this has the potential to prevent any effective HUMINT collection in theater ever again. Imagine someone telling a potential informant their identity will be protected now. Bottom line, PFC Manning has murdered hundreds of innocent Afghans who were trying to help us make their country a better place, single-handedly sabotaged Afghan trust of the American presence in their country, and potentially has kept us from ever winning that war.
I am not a fan, at all, of people who like to throw the word "treason" around every time someone's actions make our job in Iraq or Afghanistan harder. But in the case of PFC Manning, I cannot think of any other appropriate charge. He has betrayed his country from a position of extreme trust, causing literally incalculable damage that almost certainly includes the deaths of several critical allies. He has done this to show "how the first world exploits the third." His actions have given a significant tactical and strategic advantage to our enemies. Beyond Adam Gadahn and Anwar Al-Auwlaki, I cannot think of anyone else who's actions more accurately describe treason.
PFC Manning is a traitor. He may argue that he was not fully cognizant of the consequences of his actions, and that may be an argument in favor of leniency in sentencing, but it does not change the validity of the charge.