Sen. Bernie Sanders (I-VT) on Friday reacted to the incident that transpired at his Thursday rally in Phoenix, Arizona, which saw a protester unfurling a Nazi flag as the presidential hopeful stood on stage, calling it “beyond disgusting” and an “unspeakable” action against the “400,000 brave Americans [who] died trying to defeat” the ideology.

The presidential hopeful reacted to a protester waving a Nazi flag to the crowd, which occurred at his rally at the Arizona Veterans Memorial Coliseum rally on Thursday. Video shows the crowd booing the man, who was eventually escorted out of the arena. Sanders did not see the flag at the time but knew something transpired, remarking, “Whoever it was, I think they’re a little outnumbered tonight”:

Sanders told reporters on Friday that the incident is “not a question of being unsafe” at his rallies and congratulated the Phoenix police department while forcefully condemning the protester’s action:

“It’s not a question of whether I feel unsafe. What I will tell you, I didn’t see it originally. I saw a lot of people looking up and booing and all that stuff. And I didn’t learn until I left the stage that it was a swastika,” Sanders said.

“And I will simply say this. And I speak not only as a Jewish-American, I think I can speak for the families of some 400,000 American troops who died fighting Nazism, fighting fascism, that it is horrific,” he continued.

“It is beyond disgusting to see that in the United States of America, there are people who would show the emblem of Hitler and Nazism, and I was shocked to learn about that later,” he added.

Sanders explained that his events have drawn protesters in the past but acknowledged that “this was something different.”

“To have in the United States of America, somebody bringing forth the most detestable symbol in modern history — a symbol of which over 400,000 brave Americans died trying to defeat — is unspeakable,” he said. “Unspeakable.”