From: Tom Bridgeland
>Only once, prior to WW-2. They did try to invade Korea a couple of
times.

Not sure about that, I have read several accounts of Japanese forays
into China. I do personally know about the Korea invasions, having
walked through the old palace in Seoul myself, seeing a placard on every
monument noting which year the Japanese burned it down and when it was
finally rebuilt.  The period of destruction seemed to range over several
centuries.  

I will have to follow this up with some references when time allows. 

Fawn