Rudy Giuliani, promoting Donald Trump's national security plan, said Monday that in the "eight years before [President Barack] Obama came along, we didn't have any successful radical Islamic terrorist attack in the United States."

That's an apparent omission of the largest terror attack in United States history. Giuliani was mayor of New York City on Sept. 11, 2001 and in the hours after the World Trade Center fell, while then-President George W. Bush was largely unseen, he became the face of American grief and determination.

His brave and graceful performance in the weeks after the towers' collapse earned him the nickname "America's mayor" and he was soon launched into national political stardom, his name synonymous with the response to the attacks. That made his comments Monday all the more puzzling.

"Under those eight years, before Obama came along, we didn't have any successful radical Islamic terrorist attack in the United States. They all started when Clinton and Obama got into office," Giuliani said ahead of Trump's speech on national security.

The comments, which were immediately lampooned on social media, were a far cry from Giuliani's usual speeches, which are often peppered with references to the resolve New Yorkers displayed after the attacks. In fact, his discussions of the attacks were so common that Vice President Joe Biden once said of him there were "only three things he mentions in a sentence: A noun, a verb and 9/11."

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The New York Daily News lambasted the former mayor with a cover that showed the quote over the attack and blared, "Rudy's most pathetic politicizing of 9/11 yet: in sick pitch for Trump, ex-mayor despicably 'forgets.'"