Does the U.S government really have a case against Wikileaks?

In light of calls from the USA to try Julian Assange for treason (I did not even know that a foreigner operating on foreign soil could be tried for treason)
I ask, is there really much difference to what Wikileaks has done compared to other media outlets such as the Guardian http://www.guardian.co.uk/ or the NY times ?
All have published the leaked documents and all have practices of confidentiality towards their informants. What would make Assanges case unique ? because he was first to publish or because his medium is solely aimed at recieving confidential material?
The slight differences seem far to petty to build a case in my opinion, what is yours?