Donald Trump is highly unlikely to listen to national security and intelligence experts about Vladimir Putin. After all, Putin has said nice things about Trump, and Trump knows he himself has a "very good brain" from which to get advice about such things.

That isn't stopping them from trying.

First up is Michael Morell, former acting director and deputy director of the Central Intelligence Agency, Mike Vickers was the undersecretary of defense for intelligence. Both are Republicans. Both have served in the Obama administration. And both have endorsed Hillary Clinton for president. Wonder why?

The Washington Post published their open letter to Trump this morning, which includes these words, emphasis added:

Mr. Trump, with all due respect to you as the presidential nominee of the Republican Party, you cannot credibly serve as commander in chief if you embrace Russian President Vladimir Putin. The Russian leader has repeatedly shown himself to be an adversary of the United States. Putin, during his long tenure, has repeatedly pursued policies that undermine U.S. interests and those of our allies and partners. He has steadily but systematically moved Russia from a fledgling democratic state to an authoritarian one. He is the last foreign leader you should be praising.

At the Commander-in-Chief Forum on Sept. 7, you said that as long as Putin says nice things about you, you will say nice things about him. That is not a standard by which a president should make policy decisions. That should not even enter your calculus. Your only question should be “What is in the best interests of the United States?”

So, here is our challenge: Demand that Putin stop his aggressive behavior overseas. Demand that he stop his dictatorial moves at home. Tell him that you will live up to our NATO commitments and defend the Baltics if need be. Tell him that you want to work with him on solving the problems in the world — but that he must behave in order to do so. That is what a true commander in chief would do.

This open letter was covered on this morning's Morning Joe, and Congressman Michael McCaul, a Republican, from Texas of all places, relates that he has talked to Trump about Putin -- "Once KGB, always KGB" -- and that Putin is clearly trying to mess with our own democratic election.

Here is the full rush transcript via Morning Joe:

MIKA BRZEZINSKI, MSNBC HOST: Joining us now, chairman of the House Homeland Security Committee, Republican Congressman Michael McCaul of Texas. Good to have you on.

JOE SCARBOROUGH, MSNBC HOST: Mr. Chairman, great to have you here.

REP. MICHAEL MCCAUL (R), TEXAS: It's good to be here.

SCARBOROUGH: Before we talk about anything, let's talk about the remembrance yesterday at Ground Zero. Talk about how moving that was, what you saw.

MCCAUL: Well, very moving psalm as always. Very good turnout. It's the first time I've seen both presidential candidates show up to something like this. Every New York police chief was there. And when they read the names and at that takes, as you know, about four hours to read 3,000 names, you get the gravity of that moment 15 years ago.

SCARBOROUGH: Yes. Let's talk about Syria. Right now, obviously what's been going on in Syria and Aleppo has just been a nightmare and we have not responded quickly enough through the years. What should we do? What else can we do as a nation to bring peace to that region?

MCCAUL: Well, I think we've been put in a bad position. I think four years of not making a decision is a decision in and of itself. The Russians are in there now. And so how do we deal with a very complex foreign policy civil war situation? The Russian interests are very different from ours in terms of propping up Assad, stability of Syria from their point of view, and an alliance from Iran. On the other hand, we do have one thing we share, and that is going against ISIS. The problem is they haven't demonstrated that capability.

SCARBOROUGH: They just haven't done that, have they?

MCCAUL: They just haven't done --

SCARBOROUGH: They've been doing Assad's bidding.

MCCAUL: They've gone really against the rebel forces to help Assad.

SCARBOROUGH: Right.

MCCAUL: And they haven't targeted ISIS. Now, if they would join us in targeting ISIS, that would be a very positive step. But I don't really trust the Russians and I think, you know, peace through strength is what Reagan talked about and trust but verify.

You know, look, in theory it would be a great step forward but we're still a little bit cautious about it.

SCARBOROUGH: Is Vladimir Putin one of the most dangerous men on the world stage when it comes to opposing American interests?

MCCAUL: I think he's one of the -- in terms of naked aggression. I think he sees weakness and weakness invites aggression. I think that Mr. Putin has taken over Crimea. He wants to take back the Baltic statse and Ukraine. He's very aggressive in cyber attacks, including potentially on our election system going into November. So I think he's a very dangerous man. Once KGB, always KGB. Question is who do you want to stare him down in a diplomatic negotiation?

BRZEZINSKI: So do you think that the Republican nominee fully understands that, what you just said?

MCCAUL: I spoke with him yesterday. I urged caution when it comes to this man. He respects him in terms of his strength, being a strong man. I think Mr. Trump envisions himself in that light as well. But urged caution to not think that we can embrace him.

Mr. Putin is not our friend. Your father knows this very well.

(LAUGHTER)

SCARBOROUGH: He does.

BRZEZINSKI: Does Donald -- I mean it with all due respect, does Donald Trump understand that?

MCCAUL: Well, his advisers do. And I think that's important to note. He's being advised by people like myself and others that this is not -- look, if you can work with him to take out ISIS --

BRZEZINSKI: So are you saying that he doesn't but advisers do so that' will be a circle of safety around someone who doesn't get it?

MCCAUL: I think he has a respect for the man. But -- respect that he thinks he's in a better position than Hillary Clinton to sit in a room with him and stare him down.

MARK HALPERIN, BLOOMBERG POLITICS: Based on what you know, the talk of the Russians trying to interfere with our election, what would they do?

MCCAUL: I can't -- I'm not at liberty to go into much of this. It's in the classified space. There are the allegations out there that they are attempting to undermine our democracy, hitting not just Democratic Party but the Republican Party.

HALPERIN: Is it a threat that they try to, for instance, change the result by giving more -- faking more votes to one side? How would that actually interfere with the --

MCCAUL: It's unclear at this point in time what their motive is. We have seen Russia in the past demonstrate a capability to influence and mess with elections in Europe, and so we're very concerned about these latest allegations of cyber interference.

HALPERIN: And what do you think of the allegation that Vladimir Putin is somehow playing Donald Trump and manipulating him by flattering him?

MCCAUL: The response to that would be they've hit both parties. It's not like they've singled out the Democrats. They've also singled out Republicans as well. So we're not quite sure what the motivation is other than potentially to undermine our way of life, our democratic system and elections.

BRZEZINSKI: All right. Chairman Mike McCaul, thank you very much. I appreciate your candor.

SCARBOROUGH: We really appreciate you coming on.

BRZEZINSKI: Thanks for coming on.

MCCAUL: Thanks, Mika.

I don't know what is more frightening, that a vicious foreign leader is trying to undermine our election process, or that one of the candidates is so stupid and vain that he welcomes our new Russian overlord.