Republican presidential candidate Marco Rubio doubled down on Sunday on his charge that the World Trade Center came down on 9/11 because former President Bill Clinton didn’t kill Osama bin Laden when he the chance.

{mosads}”I believe that if Osama bin Laden had been killed, al Qaeda as an organization would not have grown to the point where it have conducted 9/11,” Rubio said on NBC’s “Meet the Press.”

Rubio made the statement at the Republican debate Saturday night in response to rival Donald Trump, who charged that former President George W. Bush was responsible for the attacks on Sept. 11, 2001.

“And my argument was, no, the responsibility of 9/11 falls on the fact that al Qaeda was allowed to grow and prosper and the decision was not made to take out the leader when the chance existed to do so,” Rubio said Sunday.

Rubio said Clinton has acknowledged the he regrets the decision not to take out Bin Laden. Al Qaeda was able to carry out the attacks, the Florida senator said, because it grew and prospered under bin Laden.

“Had bin Laden been taken out, it is doubtful that 9/11 would have happened, at least on September 11th of 2001, because al Qaeda would not have been in the position to be able to carry something like that out,” Rubio said.

“This is what happens when you have a chance to take out the leader of a terrorist organization, and you failed to do so. And the results are something like 9/11,” he added.