I think it's believable because it's not surprising me.
This kind of stuff is normal in war, especially in a war that has been raging for many years. War brutalizes people, it's been known for ages.
Well, hey! Who needs evidence when we can let confirmation bias do our thinking for us?

You're right that a lot of bad things happen in war, but that doesn't mean one should believe every story that comes along. Doing so is simply enabling propaganda.