For someone who wants to see the exact reply of Rav Yisrael Ariel on this subject go to the hebrew forum at
http://hayamin.org/forum/index.php/topic,37485.0.htmlI will make an attempt to translate part of his reply at this time
While there is a situation where a woman is strongly observant of the commandments and acts with Tzniut (modesty) and contirbutes to the spiritual and the security leadership of the nation of Israel, in my humble opinion (writes Rabbi Ariel) there doesn't have to be a problem (having a woman in a leadership position or the knesset).
See what our sages stated in the matter of Dvorah the female prophet (Breishit Rabba, Parshat Lech Lecha, Parsha 40) Barak said to her: if you go with me I will go and if you will not go with me I will not go! Rabbi Yehuda and Rabbi Nechemia commented.
Rabbi Yehuda said: if you will go to me to Kedesh I will go with you to Chatzor! And if you will not go with me to Kedesh-I will not go with you to Chatzor!
Rabbi Nechemia said: if you will go with me for a song of praise - I will go with you to war and if you do not go with me for a song of praise I will not go with you to war.
"And she said (replied) I will surely go with you however you shall scarcely attain honor".
That is to say in the opinion of the sages, when one has to go and battle in Kedesh and Chatzor, behold it is a time of emergency and war and therefore even a woman goes out to war!
Now going to our topic, a female member of the Knesset who observes commandments as described above is worth all the secularists in the Knesset combined, both in security issues and in matters relating to the land of Israel. Therefore, even if just for the reason
"It is a time to do for Hashem, they have annulled your Torah", the matter is permitted.
It is clear that also in the war over the holy things of Israel, this is a war, and when others,
such as secularists and Arabs, are fighting to destroy education and the world of Torah and to destroy settlements and to hand over territories to the enemy, in this matter it was stated,
"All go out, even a groom from his room and a bride from her Chupa" (Sotah page 44).
Bli Neder, G-d willing I will translate more of Rabbi Ariel's words at another time.