The actual theft resulted from a combination of ineptitude and an insider with a grudge. Pte. Bradley Manning had little trouble hacking into government computers to steal classified information that he shouldn't have had access to. The government's case against Mr. Assange hinges on the degree to which he may have instigated the theft. Being actively involved in obtaining classified information is much more serious than simply publishing it.
Now U.S. authorities are reputedly offering Mr. Manning a plea bargain in return for implicating Assange in the theft. Considering the seriousness of the charges faced by Manning, it will be difficult for him to refuse some sort of deal, but will the world see this as justice?
The American government already looks bad enough. If the rest of the world sees the prosecution of Julian Assange as nothing more than a show trial with trumped-up evidence, designed to blame foreigners for something that is really more a domestic issue, then mild resentment over the contents of the documents could turn into real hostility.
There is a big difference between American authorities making a legitimate attempt to defend against foreign attack, and using brute force, as the world's most powerful country, to launch a witch-hunt, for no other purpose than to divert attention from themselves. If the Justice Department succeeds in convicting the head of WikiLeaks of espionage, and putting him in jail for a long time, will the rest of the world see this as democracy in action, or the long arm of a vengeful Uncle Sam?
Important, powerful people don't appreciate being made to look foolish, and need their revenge. If this is the real reason for the government's aggressive pursuit of Julian Assange, and they are willing to go to any lengths to prove that this whole affair can be pinned on foreign agents, then the result could prove more humiliating than the contents of the documents.
American relations with other governments have suffered serious setbacks from these leaks. Politicians have a God-given talent for making bad situations worse, and are well on their way to turning embarrassment into diplomatic disaster.