man with glasses: who exactly was he working for *spoilers*

He could either have been:

-Spy working for Nationalist China
-Spy working for Communist China
-Japanese collaborator

Near the end of the movie, he seemed to be anti-Japanese, so that rules out #3. Plus, the Japanese tried to abduct him or his wife several times.

When the man with glasses first appears, Mao Zhai (who was still a loyal National China general) was suspicious of him and spoke of him as an enemy. So he couldn't have been working for Nationalist China.

So that leaves only option 2, him being a spy for Communist China. But there was no mention of this faction in the movie.

Who do you guys think he was working for?