Donald Trump is notorious for his Twitter rants, which have targeted, well, just about anybody and anything. This week alone, Trump has gone off on Hillary Clinton in an anti-recount tweetstorm. He has also busted out a variety of conspiracy theories and claimed—with no actual evidence—that he would have won the popular vote during the election "if you deduct the millions of people who voted illegally." And on Tuesday, Trump tweeted that flag-burners should be imprisoned for a year or have their citizenship taken away, despite the fact that the Supreme Court has already ruled that proposal unconstitutional. So during an interview with Conan O'Brien on Tuesday night, Bernie Sanders said what many people are thinking: Trump's tweets are "delusional" and "totally insane"—and also very scary.

In the interview, which you can watch above, Conan asked Bernie about Trump's election fraud conspiracy tweets. "I tell you what my take is. First of all, it's delusional. It's totally insane. Nobody believes that who studies elections or election patterns," Sanders said. "But two—this is what is scary about it—when he says that, he's really sending a signal to Republican [leaders] all over the country. What he's saying is, we've got to suppress the vote. We have got to make it harder for poor people, people of color, immigrants, elderly people, to participate because they may be voting against us. And that's scary stuff."

Sanders added, "My own view is we've got to work overtime to bring more people into the political process, not make it harder for people to participate."

Then, Conan brought up Trump's tweet from earlier that morning.

Sanders started off by noting that America has much, much bigger problems to handle. "Let's see, we have massive wealth and income inequality," Sanders said, noting our problems with poverty and climate change "which is threatening the existence of the planet." Yet, Sanders noted, Trump's "talking about three people who might burn the American flag."

However, Sanders also noted the sinister "hidden message." He explained: "What [Trump] is really saying is, 'If you really want to dissent, be careful. It's not just the American flag here, we're watching you.' That's what's scary about that."

Conan then shifted to ask Bernie, "as a citizen," how he feels about Trump. "I worry about the future of this country," Sanders said. "I worry about somebody who wins an election, whose cornerstone of his election was bigotry, was attacking Mexican-Americans, Muslims trying to divide us up."

He added: "I worry very much about a man who thinks that climate change is a hoax when the scientific community tells us that it is the most serious environmental crisis facing this planet, and if we don’t get our act together the kind of planet we’re going to leave to our kids and grandchildren will be with serious problems."

Sanders also discussed the media and how they need to "focus on the real issues facing the American people." He explained: "What media loved was the fact that Trump would say one absurd thing after another, ugly things about people we have never heard before from a presidential candidate. That was great TV. CNN's ratings went way up. I think the American people have got to demand more out of media. The American people have got to demand that media talk about the issues that impact our lives."

On the show, Sanders also touched on Hillary Clinton and Mitt Romney. You can watch his entire interview in the clip above.