Q&A: What don't we know about the Russia investigation?

WASHINGTON - Sometimes it feels as though the Russia investigation led by special counsel Robert S. Mueller III has been one bombshell after another. He's successfully prosecuted some of President Donald Trump's closest aides and provided a detailed blueprint of Moscow's attempts to interfere in U.S. politics.

But there's still a lot we don't know about the investigation, and some of the biggest questions of the case remain unanswered. Here's where major issues in the case stand and what we're still waiting to learn.

___

Question: What exactly was Moscow doing during the 2016 campaign?

Answer: This story line is the clearest part of Mueller's investigation at this point since his team has used indictments to outline