Sam, We have sat here in the Ukraine War asking this question hundreds of times. There is no answer that we can come to grips with on a rational level. Theodicy is a mystery. During Orthodox Great Lent, I read a book titled "The Sunflower" by St. John of Tobolsk. If you are really looking for a better understanding, I recommend it highly as it has brought me peace within a war zone. It doesn't answer everything but goes just far enough. On 9/11, I was driving to work at the US Coast Guard Base in Cape May, NJ for a seasonal job and used to be employed at the Taj in AC where some of the terrorists visited just before that awful day. We always remember.