Bush 'taken aback' about alleged threat to Pakistan

President Bush on Friday said he was "taken aback" by a report that a U.S. official threatened the United States would attack Pakistan if it did not help immediately after 9/11.

Bush made the remarks at a White House news conference with Pakistani President Pervez Musharraf, thanking the U.S. ally for his role in the war on terror.

The Pakistan president has told CBS News that -- immediately following the September 11, 2001, attacks -- the Bush administration threatened to bomb his country "back to the Stone Age" if Pakistan did not help in the U.S. war on terrorism.

Bush said he first heard of the alleged threat "in the newspaper today." (Watch as Bush says he's unaware of any such conversation -- 1:56)

"I was taken aback by the harshness of the words," he said.