Bernie Sanders compared the issue of online attacks from some aggressive supporters of his political revolution to Russian efforts to stoke division in the United States while also trying to disown those supporters.

A moderator question forced Sanders to address the matter during Wednesday's Democratic presidential debate in Las Vegas.

Sanders noted that he has millions of online supporters and that "99.9% of them are decent people, are working people, are people who believe in justice, compassion, and love."

"And if there are a few people who make ugly remarks, who attack trade union leaders, I disown those people. They are not part of our movement," Sanders said.

He noted that some of the black women on the Sanders campaign also receive vicious online attacks.

Supporters of the Vermont senator allegedly harassed Nevada's powerful Culinary Union with "vicious" tweets, emails, and phone calls after it offered an anti-endorsement of Sanders and expressed opposition to his single-payer "Medicare for all" healthcare plan.

Rivals of Sanders often condemn his online army, sometimes called "Bernie Bros," and the issue has become a problem for the senator as he becomes the new front-runner in national polls. New York Rep. Alexandria Ocasio-Cortez, who has endorsed Sanders, conceded on Wednesday that Sanders supporters are sometimes "hard to control."

Former South Bend, Indiana, Mayor Pete Buttigieg chimed in during the debate by saying that he believes that Sanders does not personally support the attacks. But he added, "At a certain point, you've got to ask yourself, why did this pattern arise? Why is it especially the case with your supporters?"

Sanders protested, saying that it is not "especially the case" among his supporters.

"Let me say something else about this, not being too paranoid," Sanders said. "All of us remember 2016 and what we remember is efforts by Russians and others to try to interfere in our election and divide us up."

"I'm not saying that's happening," he added.