I think they showed their hand when they shouldn't have. I know during the Cold War/times of peace sub skippers had fun popping up next to people etc etc like a hacker entering a server just to prove he can. However, at this point I wonder if that is some kind of precursor of a Chinese show of strength, since it would a very possible outcome that the sub could have been blown straight out of the water if it had been detected right before it surfaced (assumed hostile).

Does this "Song" class mean the Russians are not longer the main source of submarines for China? I know most of their subs are Russian Kilo/Akula/Oscar/Alfa, but the Chinese have come a long way since then.