In a true ISlamic society a woman can go from one end of the country to another end without any mehram along her and she was completely save.This was the real example of Islamic society in the first century of islmic state.there is no question of pardah while providing security to a woman in islamic state because if the woman is not muslim she can not be forced to have pardah but she has eqaul right of protection as a pardah dar woman has.Therefore irrespective of pardah security for woman is generally essentail in all socities and duty of Islamic state specifically.
In quran when Almighty addressd the muslims for pardah he first addressd man to lower down his eyes and then he orderd woman to cover herslf.so pardah is first essential for man then woman.if a man does not bother to look at a female infront of him after having one sight then sexual harrasment can be controlled at the first step.
It is woman own matter wheather she wants to cover her or not because whatever deeds she does in this world she ll be responsible in the next world.No body is going to force her for any act because
Islam says every body is responsible for his or her act and there is no force full conversion in Deen ISlam for any body.