Former New York City mayor Rudy Giuliani said there were no successful radical Islamic terrorist attacks before president Barack Obama entered the White House.
Speaking in Youngstown, Ohio, before Donald Trump took to the stage to reveal his plan to fight terrorism, the former mayor said the rise of radical terrorism has only occurred in the last eight years.
“Under those eight years before Obama came along, we didn’t have any successful radical Islamic terrorist attack in the United States,” Mr Giuliani said.
“They all started when Clinton and Obama got into office.”
He did not mention the terrorist attacks on 11 September 2001 in New York, when more than 2,900 people died.
His comments came as vice president Joe Biden had just finished his speech against Donald Trump in Scranton, Pennsylvania, where he called the Republican nominee’s ideas “dangerous” and “profoundly un-American”.
Mr Trump, who was working as a real estate mogul in 2001, when Mr Giuliani was mayor, has since said he saw American Muslims “cheering” as the Twin Towers fell.
He also said he donated money to help rebuild the city after the attacks, and those claims have been disputed.
His aide, Katrina Pierson, recently came under fire as she said on CNN that the US did not invade Afghanistan until president Obama came into office.
"Remember, we weren’t even in Afghanistan by this time," Ms Pierson said. "Barack Obama went into Afghanistan, creating another problem."
She later clarified that she had been referring to Syria and that "everyone makes mistakes".
Mr Giuliani said in April that he would not endorse Mr Trump but that he would vote for him in November.
He also defended Mr Trump's comments last week that president Obama "founded" Isis, the radical terrorist network.
