Extracts from the testimony given by senior US politicians to the commission investigating the 11 September 2001 attacks on America.
Donald Rumsfeld, Secretary of Defence:
I knew of no intelligence during the six-plus months leading up to September 11 that indicated terrorists would hijack commercial airliners, use them as missiles to fly into the Pentagon or the World Trade Centre towers...
But imagine that we were back before September 11 and that a US president had looked at the information then available, gone before the Congress and the world and said we need to invade Afghanistan, overthrow the Taleban and destroy the al-Qaeda terrorist network...
Mr Rumsfeld says the US had no military means to prevent 9/11
How many countries would have joined, many, any? Not likely...
Some ask why wasn't Bin Laden taken out? And if he had been hit, could it have prevented September 11?
Even if Bin Laden had been captured or killed in the weeks before September 11, no one I know believes that it would necessarily have prevented September 11.
Killing Bin Laden would not have removed al-Qaeda's sanctuary in Afghanistan.
Moreover, the sleeper cells that flew the aircraft into the World Trade towers and the Pentagon were already in the United States months before the attacks.
Indeed, if actionable intelligence had appeared, which it did not, 9/11 would likely still have happened and ironically much of the world would likely have called the September 11 attack an al-Qaeda retaliation for the US provocation of capturing or killing Bin Laden.
William Cohen, Secretary of Defence under President Clinton
Mr Cohen was US Defense Secretary until January 2001
The Clinton administration more than any previous administration understood that the threat that terrorism put to our country.
In spite of all of this... we need to do far more... to prevent terrorism reaching our shores.
Even now after September 11, it is far from clear that our society truly appreciates the gravity of the threat we face or is yet willing to do what is necessary to counter it...
After all, it is commonly noted, there have been no attacks since 9/11.
This is a dangerous delusion.
The enemy is not only coming, he has been here. He is already amongst us.
I think that we have failed to fully comprehend the gathering storm, even now...
We are all at risk now and we have to share information.
Mr Powell says President Bush was fully aware of the terrorist threat
Colin Powell, Secretary of State:
President Bush decided early on that we needed to be more aggressive...
He and his entire national security team understood that terrorism had to be among our highest priorities and it was...
Our counter-terrorism planning developed very rapidly considering the challenges of transition and of a new administration.
We were not given a counter-terrorism action plan by the previous administration.
As I mentioned, we were given good briefings on what they had been doing with respect to al-Qaeda and with respect to the Taleban...
The briefers... conveyed to us the gravity of the threat posed by al-Qaeda, but we noted early on that the actions that the previous administration had taken had not succeeded in eliminating the threat.
To get at al-Qaeda, we had to end Pakistan's support for the Taleban...
The basic elements of our new strategy which came together during these early months of the administration - first and foremost eliminate al-Qaeda.
The strategy would call for ending all sanctuaries given to al-Qaeda.
We would try to do this first through diplomacy, but if diplomacy failed and there was a call for additional measures including military operations, we would be prepared to do it.
Madeleine Albright, Secretary of State under President Clinton:
We can't turn back the clock to before 11 September but we must do everything we can to prevent similar tragedies and we owe it to the families of the victims of 9/11and to us all.
Madeleine Albright defended the Clinton government's record
Mr Chairman, we all know that history is lived forward and written backward.
Much seems obvious now that was less clear prior to 11 September.
But I can say with confidence that President Clinton and his team did everything we could, everything we could think of based on the knowledge we had to protect our people and disrupt and defeat al-Qaeda...
The president was prepared to order military action to capture or kill bin Laden. If we had had the predictive intelligence we needed, we would have done so ... and I would have strongly supported that step...
If we pursue goals that are unnecessarily broad such as the elimination not only of threats but also of potential threats, we will stretch ourselves to the breaking point and become more vulnerable, not less, to those truly in a position to harm us.
We also need to remember that al-Qaeda is not a criminal gang that can simply be rounded up and put behind bars.
It is the centre of an ideological virus that has wholly perverted the minds of thousands and distorted the thinking of thousands more.
Until the right medicine is found, the virus will continue to spread... We must be sure that Bin Laden goes down in history a murderer, a traitor to Islam and a loser.