CNN political analyst David Gergen warned on Sunday's edition of 'Reliable Sources' that the threat of "authoritarian rule" in the U.S. is growing because of President Trump's response to Russia's meddling in the 2016 election. "A dozen countries have flipped from democracy to authoritarianism since the Cold War," Gergen warned. "We're not immune to that." In response to host Brian Stelter's <a href="https://www.realclearpolitics.com/video/2018/02/18/cnns_stelter_president_trumps_latest_tweetstorm_makes_him_appear_deeply_troubled_unhinged.html">monologue about the president's "unhinged" tweetstorm about Robert Mueller on Sunday morning</a>, Gergen said that the way Trump speaks is "eroding the trust in the presidency" and has been "extremely damaging" to the national unity of the U.S. in general. <blockquote class="twitter-tweet" data-lang="en"><p lang="en" dir="ltr">If it was the GOAL of Russia to create discord, disruption and chaos within the U.S. then, with all of the Committee Hearings, Investigations and Party hatred, they have succeeded beyond their wildest dreams. They are laughing their asses off in Moscow. Get smart America!</p>— Donald J. Trump (@realDonaldTrump) <a href="https://twitter.com/realDonaldTrump/status/965212168449941505?ref_src=twsrc%5Etfw">February 18, 2018</a></blockquote> <script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script> "And the Russians are laughing at us because they are getting away with this," Gergen said. "They are fomenting much of this, and there is no sense of urgency [from Trump]." "We have an election that's just around the corner later this year. What if the Democrats take the House back? Is all of that going to be blamed on fake news? What if they fall short? Are Democrats going to think, you know, it was all that meddling, and they have won a few seats that they wouldn't have otherwise won," he warned. "It is the beginnings, in many other countries it's been the beginnings of an authoritarian rule, and that's the larger threat hanging over us now," Gergen said. He continued: "I find it the threat is growing. There is a new book out about <a href="https://www.amazon.com/How-Democracies-Die-Steven-Levitsky/dp/1524762938">How Democracies Die</a>, written by two Harvard professors and it’s quite striking about the number of countries that were led by democratically elected leaders, but they turned more and more authoritarian. A dozen countries have flipped from democracy to authoritarianism since the Cold War. We’re not immune to that. I think we have strong checks and balances, thank God we have long traditions and norms, but we have to protect those, in a bipartisan way."