If you doubt it, note that he is no pacifist opposed to war and killing. He has just decided that he'd prefer our troops and our allies die rather than other people:
Any U.S. and allied casualties that result from the publication of classified Afghan war documents would be an acceptable risk, WikiLeaks founder Julian Assange suggested Monday, saying "such information is also likely to save a great many lives."
This is no dissent. Assange not being an American is only the starting point of that assessment.
Assange is on the other side waging war on us. How do we respond?