And what I really like about this plot is that the Federation isn't involved, this is a major interstellar event involving three alien empires and yet we still care and feel like it matters.
This episode, and its predecessor, have a lot going for them, but this is the one item that seals them both as five star episodes for me. DS9 was able to take three governments/cultures/empires (call them what you will) and craft a compelling narrative around them without having to rely on using the entity we're naturally most familiar with - the Federation. That's a sure sign of excellent storytelling and writing right there. They were able to make us care about what were essentially pieces of the background in other shows just as much as we care about the "hero" society. Outstanding.