This is one of the reason I favor the death penalty for traitors and spies.
Would you also be in favor of the death penalty for OUR spies who are caught? Here's a news flash for you: Everybody spies on one another. It's a game. In the spy game, you jail them until such time as a good trade comes up (not that this particular trade, if true, qualifies).
Traitors should be summarily executed in every case, with hout exception. I would also add terrorists to this list.