So, what really happened?

First, it is clear the US authorities did little or nothing to pre-empt the events of 9/11. It is known that at least 11 countries provided advance warning to the US of the 9/11 attacks. Two senior Mossad experts were sent to Washington in August 2001 to alert the CIA and FBI to a cell of 200 terrorists said to be preparing a big operation (Daily Telegraph, September 16 2001). The list they provided included the names of four of the 9/11 hijackers, none of whom was arrested.

It had been known as early as 1996 that there were plans to hit Washington targets with aeroplanes. Then in 1999 a US national intelligence council report noted that "al-Qaida suicide bombers could crash-land an aircraft packed with high explosives into the Pentagon, the headquarters of the CIA, or the White House".

Fifteen of the 9/11 hijackers obtained their visas in Saudi Arabia. Michael Springman, the former head of the American visa bureau in Jeddah, has stated that since 1987 the CIA had been illicitly issuing visas to unqualified applicants from the Middle East and bringing them to the US for training in terrorism for the Afghan war in collaboration with Bin Laden (BBC, November 6 2001). It seems this operation continued after the Afghan war for other purposes. It is also reported that five of the hijackers received training at secure US military installations in the 1990s (Newsweek, September 15 2001).

Instructive leads prior to 9/11 were not followed up. French Moroccan flight student Zacarias Moussaoui (now thought to be the 20th hijacker) was arrested in August 2001 after an instructor reported he showed a suspicious interest in learning how to steer large airliners. When US agents learned from French intelligence he had radical Islamist ties, they sought a warrant to search his computer, which contained clues to the September 11 mission (Times, November 3 2001). But they were turned down by the FBI. One agent wrote, a month before 9/11, that Moussaoui might be planning to crash into the Twin Towers (Newsweek, May 20 2002).

All of this makes it all the more astonishing - on the war on terrorism perspective - that there was such slow reaction on September 11 itself. The first hijacking was suspected at not later than 8.20am, and the last hijacked aircraft crashed in Pennsylvania at 10.06am. Not a single fighter plane was scrambled to investigate from the US Andrews airforce base, just 10 miles from Washington DC, until after the third plane had hit the Pentagon at 9.38 am. Why not? There were standard FAA intercept procedures for hijacked aircraft before 9/11. Between September 2000 and June 2001 the US military launched fighter aircraft on 67 occasions to chase suspicious aircraft (AP, August 13 2002). It is a US legal requirement that once an aircraft has moved significantly off its flight plan, fighter planes are sent up to investigate.

Was this inaction simply the result of key people disregarding, or being ignorant of, the evidence? Or could US air security operations have been deliberately stood down on September 11? If so, why, and on whose authority? The former US federal crimes prosecutor, John Loftus, has said: "The information provided by European intelligence services prior to 9/11 was so extensive that it is no longer possible for either the CIA or FBI to assert a defence of incompetence."

The professional golfer Payne Steward died aboard his chartered jet when the cabin suffered explosive decompression. The plane continued to fly on auto-pilot. It took the ground controllers 21 minutes to summon an F-16 fighter to come in behind the doomed jet to investigate. On September 11, there was a squadron of F-16s and a squadron of FA-18s laagered up at Andrew's Air Force Base, which sits just 12 miles from the White House. The hijacked commercial planes were in the air, and were crashing into buildings, for almost two hours before one single fighter turned a wheel and took to the sky. Payne Stewart rated a fighter in 21 minutes. Hundreds of kidnapped civilians did not rate a fighter for almost 120 minutes, until the horror was already over. The mantra for this says, "Incompetence," yet no one has been fired or even reprimanded.