Arso, interesting admit Rav Chaim Kanievsky. I saw a newspaper clipping from the period- it ran a headline on the Rebbes claim- it didn’t say several Torah leaders including the Lubavitcher Rebbe claim…
Was he public about it?
Secondly, you have homework now: (I’ve saved mine from the other day): 1. Proof that The Rebbe said not one Jew will die
2. Proof for your claim that indeed two Jews died directly from the rockets