Shalom,  I am now translating all my sources from Hebrew to English and very shortly will print a book with all the exact sources I am talking about The book that I am referring to about your question is called 'Lev Eliyahu' at the end of the Parash Yitro. This is brought down from Rabbu Elchanan Vaserman who was his great student and Rabbi Yoram Abarjil testified to that Another book of the Chofetz Chayim talking about WW3 is called 'Mishna Berura' where he is explaining why we read the Haftora of Gog U'magog on Shabbat Chol Hamoed And the third is in the Chofetz Chayim's book called 'Otzrot Acharit Hayamim' אוצרות אחרית הימים in the part talking about the Gog U'magog war part 34 There are more sources but you'll have to wait patiently for the book with all of them that will come out shortly All the best, Rabbi Anava