MSNBC Host Joe Scarborough ominously warned on Tuesday that President Donald Trump is opening the door “for cruelty and genocide” by calling disgruntled former White House aide Omarosa a “dog.”

Scarborough made his remarks after Trump praised White House Chief of Staff John Kelly for “quickly firing that dog” Omarosa in a tweet that also referred to Omarosa as a “crazed, crying lowlife.”

“We’ve heard it said before and we’ve heard it discussed before about how tyrants and autocrats and, yes, fascists, communists, others have used the language of dehumanization to justify… a movement away from democracy and a movement away from decent standards,” Scarborough said.

The Morning Joe co-host said he spent some time searching about “why certain leaders do that” and referenced an NPR article about David Livingstone Smith’s book, Less Than Human.

“As NPR explained during the interview, during the Holocaust, Nazis referred to Jews as rats. In Rwanda, genocide was often justified with calling Tutsis cockroaches. Slave owners throughout history considered slaves subhuman animals.” Scarborough continued. “That was one of the key takeaways from the book Less Than Human. And it argues that it’s important to define and describe dehumanization because… it opens the door for cruelty and genocide.”

Scarborough said that “nobody is saying that Donald Trump is a Nazi, nobody is saying that he’s Adolf Hitler in 1938, 1939, 1940.”

But then he again tried to make the case that Trump is acting like dictators who have opened the door to “cruelty” and “genocide.”

“But you can see time and time again… this is actually how dictators and tyrants open the door, and they do it by dehumanizing their political opponents,” Scarborough said before blasting Trump for referring to illegal immigrants in sanctuary cities as “breeders” like they were “animals, dogs, mules.”

Scarborough’s comments were reminiscent of California Lieutenant Governor and gubernatorial candidate Gavin Newsom’s sensationalistic charge in May that Trump’s “hateful rhetoric” against illegal immigrant MS-13 gangsters is the kind that “leads to hate crimes and genocides.”

Newsom made his remarks after Trump called MS-13 illegal immigrant gangsters “animals.”