Pollard's Life Sentence

My insightful post on the Jonathan Pollard case, which I'm too lazy to retype in full, was based on this statement:

Pollard's life sentence was the most severe prison term ever given for spying for an ally.

Of course, life imprisonment is always the most severe prison term ever given for any crime. I think Gearan means to say that Pollard is the only one who has received a life sentence for spying on/against the United States on behalf of an ally. But my question is: how many people have been convicted of spying on the U.S. on behalf of an ally? Is it really a meaningful comparison? I know Pollard's supporters say he got railroaded by that sleazebag Cap Weinberger, who presented evidence to the court that Pollard never got to see (at least during the trial), but I still can't manage any sympathy for him.