The head of the Anti-Defamation League demanded Sunday that technology giants help curtail bigoted rhetoric being spread online.

"Not only is the political environment contributing to this, social media is amplifying and accelerating it in shocking ways," Jonathan Greenblatt, ADL's CEO and national director, said during an interview with NBC News' "Meet the Press." "And so Silicon Valley is part of the problem and needs to be part of the solution."

Greenblatt, whose organization has deemed Saturday's Pittsburgh synagogue shooting the "deadliest anti-Semitic attack in U.S. history,” undermined President Trump's doubts that such assaults could happen "in this day and age."

"I don't know that it ever went away. The ADL worked to fight it the '40s, '50s, and '60s, and today we're seeing this resurgence," he said.

"We are seeing an environment in which anti-Semitism has moved from the margins into the mainstream as political candidates and people in public life now literally repeat the rhetoric of white supremacists," Greenblatt continued. "And they think it's normal and permissible to talk about Jewish conspiracies, manipulating events, or Jewish financiers somehow controlling activities, and that is awful."

At least 11 people were killed and six others injured, including four police officers, when a gunman walked into Pittsburgh's Tree of Life Synagogue Saturday morning and opened fire while shouting anti-Semitic remarks. The shooting suspect, Robert Bowers, 46, faces 29 separate federal charges, including hate crimes. A majority of those charges are punishable by death.