Can't invade Japan

[Grotius]

I have a question about invading Japan. As the attached screenshot indicates, I've taken Hokkaido, and my aircraft have eliminated all defenders from Kyushu. But I can't seem to conduct an amphibious assault from Hokkaido to Kyushu -- or, for that matter, from anywhere to Kyushu. It doesn't seem to matter where I put my transports; in any adjacent sea region, they don't seem to want to support an invasion. I've got plenty of supply at Hokkaido (and elsewhere), and no units have yet moved this turn, other than a few aircraft.

Also, when I play as Japan, I routinely strategically move stuff from Tokyo to Hokkaido. I assume one has to own both Hokkaido and Honshu (Tokyo) to do this?

Anyway, what am I doing wrong with my invasion? This is an AI game, version 1.106.

[Uncle_Joe]

Let me guess, its a Winter turn?

Cant invade 'cold' areas in the Winter...

Had the same problem trying to invade France once from Britain...

[Grotius]

Doh, that would seem to be it. It's Winter 1946.

Thanks. [:)]