Very few are even aware of these plots, because fortunately, despite the terrorists' meticulous preparation, they were never carried out. Had it not been for one especially observant CIA officer, the terrorists could have sent several hundred airline passengers and their crews plummeting to their deaths.
This CIA officer's acute observation alerted him to a plot designed to mark the fifth anniversary of 9/11. On being notified by the Americans, British intelligence personnel made lightning strikes on homes in northeast London and captured the plotters before they could carry out their plans. Terror was averted, thanks to USA's security personnel, chiefly the CIA.
Yet today, the hitherto best intelligence systems in the US may not prevent another terrorist strike, thanks to President Barack Hussein Obama.
Senior former White House speechwriter Marc A. Thiessen, in his book Courting Disaster, alleges that "in his first forty-eight hours in office, President Barak Obama shut the (CIA) program down", and, further, that "Barack Obama arguably did more damage to America's national security in his first 100 days in office than any president in American history".
These are strong assertions. Thiessen backs them up with a wealth of evidence. His study is solid, wide-ranging and backed by his own experience as an insider in the highest echelons of America's political life.
Courting Disaster deserves a wide readership. Here the reader is given "some of the most sensitive intelligence information ... the secrets behind how the CIA successfully interrogated the men who killed thousands on September 11, 2001, and stopped them from killing thousands more".
Lest he be accused of irresponsibly revealing sensitive intelligence he says that "when Obama took office ... (he) released reams of highly classified documents describing the details of our nation's interrogation policies". If anyone handled vital intelligence irresponsibly it was not Thiessen but Obama.
Worse, the US President declared that American intelligence personnel were guilty of committing acts of torture, a point Thiessen strongly refutes.
When Obama released highly classified documents to the public, three terrible results followed. First came a flood of recriminations against US intelligence personnel, the very people whose work had protected the free world. Next, America's enemies were now in possession of details about the CIA's interrogation procedures which had yielded the very information which has, since 9/11, protected the US from further terrorist attacks. Finally, President Obama's Attorney-General Eric Holder considered laying criminal charges against CIA officials.
Thiessen shows that America's safety since 9/11 is directly due to the CIA's work. It was the CIA's work which successfully averted the 2006 airline terrorist plot, which was planned by al-Qaeda to coincide with the fifth anniversary of 9/11. It is not too much to say that the CIA is the only reason that 9/11 has not been repeated.
But now disaster may strike again and, if it does, according to Thiessen, Obama must be held responsible for undermining America's first line of defence: the intelligence systems established by prior administrations.
Obama's hasty and ill-considered disclosure inadvertently helped those who for years have targeted the CIA with a dishonest campaign of smear and seditious tactics. Various academics, journalists and media spokesmen, not to mention some of the US's most virulent enemies, have collaborated in sabotaging America's freedom and helping its enemies. Their frequent accusations that the CIA has engaged in torture - a practice contrary to the Geneva Convention on the humanitarian treatment of prisoners of war - have played into the hands of terrorists around the world.
Thiessen is no conspiracy theorist and never resorts to unsubstantiated speculation. Instead, he marshals abundant evidence to demonstrate how Obama has imperilled America and the free world.
Thiessen is well qualified to offer this critique. His 15-year national security career took him from Capitol Hill to the Pentagon and then to the West Wing. There he served on the White House senior staff as chief speechwriter for Secretary of Defense Donald Rumsfield and later for President George W. Bush.
He was given the historic assignment of crafting one of President Bush's most important speeches in which he revealed the existence of the CIA program of detention and interrogation, and justified why he had authorised the transfer of Khalid Sheikh Mohammed and other terrorists to Guantanamo Bay for trial. (Khalid was the chief architect of the deadly 9/11 attack. His capture in itself is an extraordinary story.)
Thiessen worked on the President's speech, with only a few others aware of his role. It was copiously researched. It went through 16 drafts, all of them marked "Top Secret/SCI", the highest level of classification there was.
Its purpose was to combat the hostile climate of suspicion, sabotage and false media reporting directed against the President and the CIA. It was hoped that Bush's speech would win congressional support for the CIA's intelligence and interrogation activities (and it did).
For this reason, Thiessen was privy to top-secret intelligence, knowledge of the inner workings of the CIA (especially its interrogation protocols), and high-level White House discussions which ranged across all of the US's security needs.
He refutes left-wing ideologues who, for political or other reasons, have accused the CIA of acting contrary to international or domestic law by resorting to the use of enhanced interrogation techniques.
When President Bush was predictably attacked by the left-liberal US media for denying Geneva Convention protections to al-Qaeda and Taliban fighters, Bush's then National Security Advisor Stephen Hadley responded by saying: "We defended the Geneva Conventions, and al-Qaeda violated them in every respect. They hid among civilians to protect themselves and killed innocent civilians to achieve their purpose."
Furthermore under the Geneva Convention, terrorists do not qualify for prisoner of war protections. To give them such privileges would undermine the very purpose of the Geneva Convention.
One persistent allegation against the CIA was that water-boarding was a form of torture. Given the fact that water-boarding is used in the routine training of US marines, this allegation is absurd. No one has ever suggested that the US Army uses tortures during its training. Moreover, water-boarding was only used on the rarest occasions and under the strictest medical supervision.
In fact, CIA interrogators received 250 hours of training before they were given such assignments. Thiessen shows that great probity was observed before water-boarding was approved for Abu Zubaydah, a top aide to Osama bin Laden and the first senior terrorist captured following the 9/11 attacks. This was permitted only in keeping with two classified memoranda from the Office of Legal Council. They required the presence of both a physician and a psychologist when water-boarding was used.
One of Thiessen's appendices is titled "The Cheney Documents". For five months, Bush's Vice-President Dick Cheney requested the Obama Administration to declassify and release CIA documents prepared in 2004 and 2005. They showed how the CIA's enhanced interrogation techniques brought to light invaluable, life-saving intelligence. They also vindicated the Bush Administration's policies on enhanced methods which had resulted in terrorist cells being broken up and American lives saved.
For five months, the Obama Administration refused the request. When the CIA documents were finally released, they were ignored by the mainstream media. Clearly, the media were only interested in sensational stories which discredited rather than vindicated George Bush's policies.
Thiessen's book is an eye-opener to the clandestine world of CIA activities. The author does not pretend that the CIA is perfect, and some criticism of the Agency may indeed be justified.
However, as Thiessen demonstrates, its role in protecting America is well attested. His purpose is to remind the public of the good the CIA has done and to underscore the fact that it has been the CIA which more than any other agency has averted repeats of the 9/11 terrorist attacks.
But Thiessen's message is sobering. Under the present Obama Administration, the CIA is being prevented from fulfilling its role. According to Thiessen's observations, President Obama himself, by his policies, is making the US vulnerable to future attacks.
Readers will determine for themselves whether Thiessen has made a convincing case.
The Revd Dr Dallas Clarnette is a retired Presbyterian minister and chairman of the Victorian branch of the Christian Democratic Party.