In general citizens have no obligation to protect classified information if it falls into their hands. This (and freedom of the press in general) is what has al

In general citizens have no obligation to protect classified information if it falls into their hands. This (and freedom of the press in general) is what has allowed newspapers to print classified material if they get a hold of it. However going out of your way to entice classified material into your possession is not similarly protected (we'd call them "spies" or "moles" on any other day), so if the government can show that Assange had any control whatsoever over what either Manning or Snowden leaked then I suppose it's theoretically possible the U.S. could charge Assange that way.