MICHEL MARTIN, HOST:

To understand where Mueller's investigation could go next, we're joined now by David Kris. He's a former U.S. assistant attorney general for the National Security Division of the Department of Justice. He's now founder of the Culper Partners consulting firm. Mr. Kris, thanks so much for talking with us.

DAVID KRIS: My pleasure.

MARTIN: You wrote on Twitter that the indictment, quote, "fills a major gap in Mueller's mosaic," unquote. Can you say a little bit more about what you mean by that?

KRIS: Yeah. Prior to this we'd seen indictments involving propaganda - both overt and covert propaganda - the exchange of things of value, and, of course, concealment and lying. But until this indictment, we hadn't seen any charges related to hacking of the DNC and the Clinton campaign, which was, after all, a major part of the Russian election interference efforts.

MARTIN: So one of the big questions that still remains, though, is whether any Americans were involved in these Russian activities. We don't get any sense of that from this.

KRIS: Well, the indictment describes some interactions with Americans, but it certainly doesn't charge any Americans. It looks to me like the special counsel is following standard investigative procedure, which is no surprise. Typically, in these kinds of complex investigations, you begin with what I'll call the outer ring of the criminal conduct, meaning you sort of go after the low-hanging fruit. And then if the evidence warrants, you begin working your way in towards the bull's-eye.

I think what we have seen now is sort of the rounding out of the essential elements of the election interference scheme, the outer ring. And I would say the next steps, depending on what the evidence shows, will involve moving in towards the center of the bull's-eye.

MARTIN: And before we let you go, this really is a matter of opinion, and this is the kind of question that every citizen has a right to kind of think about for himself or herself. But let's say, for the sake of argument, that this is it, that this is a Russian-inspired operation for the purpose of advancing their own national goals as they understand them. So they targeted the Democrats. They targeted Hillary Clinton for their reasons and that no Americans were involved - is it still worth it to have gone through this exercise even if - there's a very remote possibility that any of these people will actually be tried in the United States. Do you feel it was worth it?

KRIS: Well, I certainly do. I guess it's a matter of opinion. But I think everyone would agree that an effort by a foreign power to interfere with our election, that's a very, very significant matter in and of its own right, regardless of whether any U.S. persons were willingly involved. This is an attack on our democracy. It is in a way a kind of a virus being introduced into the American body politic, and we need to be able to develop antibodies to that virus.

The special counsel's indictment, through its public educational function, is one way in which we may be able to begin developing those antibodies to resist future foreign efforts to influence our elections improperly. And I would say that that, in and of itself, is a very important goal for American democracy.

MARTIN: That's David Kris. He's a former US assistant attorney general for the National Security Division of the Department of Justice. And now, he's founder of Culper Partners consulting firm. David Kris, thanks so much for talking with us.

KRIS: My pleasure. Transcript provided by NPR, Copyright NPR.