Anywhere that has had a war, as people abandon their pets when they flee. Join the pack or get eaten and still you may not be safe. Having said that there must be other reasons that cause this too as there was a pack in Oman when I was out there (and clearly the variety of breeds they had been pets) more nuisance than dangerous though.
I have been to Ukraine and that was 10 yrs ago, if you enter a park and see a pack of dogs it is best to avoid them. It blows me away that they don't have animal control there, and that story is quite sad, and should never have happened.
@LynnUK I visited Ukraine 10yrs ago. There were dogs all over the place, usually 2 or 3 together. I did go to a park and about 10 of them running around, and decided to leave. It is hard to believe that they allow this to go on.