Espionage is The act of obtaining, delivering, transmitting, communicating, or receiving information about the national defense with an intent, or reason to believe, that the information may be used to the injury of the United States or to the advantage of any foreign nation. Espionage is a violation of 18 United States Code 792-798.

Snowden was passing information to the American people. I'm having a pretty hard time seeing just how that could be espionage.

Onward and upward,
airforce