Should we say Hallel today in light of the elimination of this arch enemy! Surely the Jewish people can say we have been saved from destruction by this news?

Shalom Roger, It is true that we, as well as every moral person in the world, should rejoice when the terrorists and haters of Israel who wish to eradicate us are killed, as Dvora the prophetess rejoices upon the killing of Sisera, “So too should all of the enemies of G-d be obliterated!” (Shoftim 5, 31). All of the enemies of Israel are the enemies of the G-d of Israel, the G-d of morality and justice. Nevertheless, there are very clear guidelines when we thank Hashem davka with Hallel (see Talmud, Psachim 117a and Megilla 14), that is only when there as an actual immediate threat against the nation of Israel in the Land of Israel. With Love of Israel, Rav Ari Shvat