President Obama called George W. Bush and Bill Clinton on Sunday before he announced that Osama bin Laden had been killed, a White House official told reporters on a conference call.

Obama called Bush and Clinton to "preview" his statement, said the senior administration official, who refused to be identified on the call.

The official also said that Obama chaired five national security meetings since March to discuss intelligence on Osama bin Laden. Those meetings, the official said, were on March 14, March 19, April 12, April 19 and April 28. Obama authorized the attack on bin Laden on Friday, April 29, the official said.

In his statement announcing the killing of bin Laden, Obama mentioned Bush once.

"We must also reaffirm that the United States is not, and never will be, at war with Islam. I’ve made clear, just as President Bush did shortly after 9/11, that our war is not against Islam," Obama said. "Bin Laden was not a Muslim leader. He was a mass murderer of Muslims."

Obama, who spoke for 10 minutes, recalled a sense of unity after the Sept. 11 attacks and said that the United States went to war "to protect our citizens, our friends, and our allies." He also gave a message to the families of 9/11 victims: "We have never forgotten your loss, nor wavered in our commitment to see that we do whatever it takes to prevent another attack on our shores."

"And tonight, let us think back to the sense of unity that prevailed on 9/11," Obama said. "I know that it has, at times, frayed. Yet today’s achievement is a testament to the greatness of our country and the determination of the American people."