Ukraine

I'm trying to figure out the significance of Putin "recognizing the independence" of those two regions they're talking about in the news.

All the stories read as if everyone already knows what that means. What does it mean... and why is it a further sign he's about to invade Ukraine?

They cite the headline, then move on to what the US is doing in response. But WHHHHY does that warrant a response? It's driving me a little batty not understanding it.