Even at war, the USA was still much more "liberal" than Nazi Germany or Imperial Japan: for starters, they didn't put any German citizens / German descendants in a concentration camp.

The Japanese descendants/citizens living in the USA were treated different because of racism. You can argue that having a racist government isn't compatible with being "liberal", but it's a matter of degree. Having a democracy that doesn't allow non whites to vote is still more "liberal" than having a monarchy / dictatorship