what are you talking about? The cold war ended in between Act 2/3 in a full out war. Did you even pay attention to the story?
this bothers me as well. People in the lore forums have made many posts that make it obvious that they either never played to act 3 or didn't pay any attention.
HEY, PEOPLE, the war is full on after Hoth. By the time you land on Belsavis for the first time, the peace is over.