How atack Antartico.

Hi. I´m play in Supremacy Colonial. For finish the game only need take two cities in Antartica. I had one thousend laps and try but i can´t atack it. After many turns I find no place where I am allowed to attack.
Somebody can help me?

My game: http://es.atwar-game.com/games/?link=4283890328

Thanks.

You already got units there to wall, whats the issue?

I've tried but the game does not give me the option to attack and brand me as a prohibited movement .

Are there any special way to do it?