'Shoot-down' order was given

The president feared other planes had been hijacked

President Bush has confirmed that he ordered any airliners refusing to turn away from Washington be shot down in the aftermath of the attack on the Pentagon, and the World Trade Center in New York.

Asked whether he had struggled with the decision, Mr Bush said: "I gave our military the orders necessary to protect Americans, do whatever it would take to protect Americans."

You've got an airplane full of American citizens ... Are you going to in fact shoot it down, obviously, and kill all those Americans on board?

Vice President Dick Cheney

"Never in anybody's thought process about how to protect Americans did we ever think the evil-doers would fly not one, but four commercial aircraft into precious US targets. Never."

Vice President Dick Cheney confirmed that the order came after World Trade Center and Pentagon had been hit, and a fourth plane appeared to be on course for the capital.

"I wholeheartedly concurred in the decision he made, that if the plane would not divert, if they wouldn't pay any attention to instructions to move away from the city, as a last resort our pilots were authorised to take them out," said Mr Cheney.

President targeted

US officials have said that the White House or even Air Force One might have been targets for that jet, United Airlines Flight 93.

Dick Cheney said shooting down the planes would have been justified

The aircraft crashed in a rural area of south western Pennsylvania. "As it turned out, we did not have to execute that decision," said Mr Cheney.

"People say that's a horrendous decision to make. Well, it is. You've got an airplane full of American citizens - civilians - captured by terrorists. Are you going to in fact shoot it down, obviously, and kill all those Americans on board?"

The alternative, he said, could have been worse.

"If we had the opportunity to take out the two aircraft that hit the World Trade Center, would we have been justified in doing it? I think absolutely we would have."

'Problem' aircraft

"There were a few moments when we thought we might, when planes were incoming and we didn't know whether or not they were a problem aircraft until they diverted and had gone elsewhere," he added.

F16 fighter aircraft were scrambled

"We had reports ... that there were six airplanes that might have been hijacked, and that's what we started working off, that list of six."

President Bush was in Sarasota, Florida at the time of the attack, but in light of the apparent threats to the presidential plane and White House, was taken to Air Force bases in Louisiana and Nebraska.

Mr Cheney said that he strongly advised Mr Bush not to come directly back.