As a Spharadi should I say Hallel with a Bracha on Yom Haatzmaut?
There is no diference between Spharadim and Ashkenazim regarding the obligation to thank Hashem for the miracles and the wonders he did and does to us all the time. That is the ruling of the Rabbanut Rashit. Regarding the Bracha on Yom Haatzmaut the issue remains open and there is no difference between Spharadim and Ashkenazim, but Spharadim are more used to saying Hallel without a Bracha like on Rosh Chodesh and Pesach. But there, unlike Yom Haatzmaut there isn't a Takana obligating saying Hallel. On Yom Yerushalaim the Rabbanut Harashit ruled that all must say Hallel with a Bracha. Rabbi Yakov Ariel