In 1950, China was willing to go to war to save their fellow Communists.  But the PRC does not really seem to care, any more, about Communism as an international movement.  I suspect they now regard Kim Kong-il's regime as an embarrassing crazy relative, nothing more.
On the other hand, they would not like to see the peninsula reunited under the South Korean government -- that would place an American ally on their border.
				
			On the other hand, they would not like to see the peninsula reunited under the South Korean government -- that would place an American ally on their border.