It is not another Iraq. Iraq has a very specific nationality problem between Shi'ya and Sunni, and it is a separate nation from 1920s. People in both side of Korea are connected through blood and family relationship, South Korea have a very strong will to help restore the government/police/economic system in NK. The U.S. wouldn't have got into such bizarre situation as in Iraq.
The whole Shi'a/Sunni division is blown out of proportion by intelligence agencies, both foreign and local, trying to alienate Iran.
If the Koreans are "connected", the Iraqis are intertwined. Intermarriage is very common, with couples maintaining their own sectarian identity.
I was raised as Sunni (not in Iraq) but have attended a Shi'ite religious school for a whole year .. without realizing. That's how similar the two are.