Settlement under attack message?! (Base game or mod?)

Hey folks, I am quite new to fo4 and I am not sure, if this message shown in the image belongs to a mod I have installed (maybe one called "enhanced gameplay"?!) OR if this is simply part of the base game??

Because this message comes up very often and I even do not know WHICH settlement is under attack...

So maybe you can help me, and tell me if this is part of base game ord maybe mod...

Best regards! Thanks