Mueller’s interest in Trump Organization centers on Russian oligarch who set up Trump Tower meeting: authors
Robert Mueller, the Special Counsel overseeing the investigation into possible collusion between Russians and the Trump campaign in the 2016 election, continues to keep his cards close to his chest as his probe circles the White House AFP/File / SAUL LOEB

Appearing on CNN's New Day on Friday morning, the authors of a new on book detailing President Donald Trump's relationship with Russia throughout the years were asked what they made of Special Counsel Robert Mueller's bombshell subpoena on Thursday to the Trump Organization seeking documents about its past dealings inside Russia.

Speaking with host Chris Cuomo, authors David Corn and Michael Isikoff -- whose book "Russian Roulette: The Inside Story of Putin's War on America and the Election of Donald Trump" was just released -- pointed the host in the direction of a Russian oligarch with longtime ties to Trump.

"The idea of Mueller dropping subpoenas on the Trump organization, I'm not spending time on Trump saying it crosses a red line," Cuomo began. "Do you think it's an indication this is about buttoning up the counter-terrorism aspect of this, or it could come from the arises out of part of the purview, which may be there may be time left in this investigation?"

"I think the investigation goes on for quite a while," Corn replied. "The Iran-Contra investigation went on for awhile, they spent six or seven years working on that. I have no reason to believe we are coming to any conclusion soon. One of my least favorite cliches is 'this the tip of the iceberg.' But with Mueller it is very appropriate; those dealing with Russia, maybe dealing with other things, shows me he is serious. If he sees anything out there, anything out there that looks untoward, he's going to look."

"If you want to understand why Mueller is doing what he's doing with the subpoena, I can direct you to the chapters, starting with chapter one, at the center of the investigation," Isiskoff added. "One major incident was the notorious Trump Tower meeting. Who set up the Trump Tower meeting? Agalarov, the Russian billionaire oligarch, who was known as Putin's builder, who Trump partnered with, first on Miss Universe, and then plans to build that first Trump Tower project in Moscow."

"It is important to know that the contact from the Russian government to the Trump campaign, to Don Trump Jr., Jared Kushner and Paul Manafort came through Agalarov, this business partnership that Trump had had for several years," Corn interjected. "I can see several subpoenas for that. And then another Trump Tower deal with a company we discovered in Russia that has very shady owners and offshore companies in Cyprus."

You can watch the video below via CNN: