Mr Richard Clarke has thrown the cat among the White House pigeons with his allegations that the Bush administration systematically underestimated the threat from al-Qaeda before the September 11th 2001 attacks on New York and Washington.
He says Mr Bush and his colleagues were fixated on Iraq instead. In a scathing judgment he writes that Mr Bush "launched an unnecessary and costly war in Iraq that strengthened the fundamentalist radical Islamic terrorist movement worldwide".
Mr Clarke carries undoubted authority as a counter-intelligence officer for more than 30 years who served under four successive presidents in the White House as policy co-ordinator on the subject. A sure indication that political blows have been struck against this administration is when the vice-president, Mr Richard Cheney, comes into the fray. He dismissed Mr Clarke's case, made on a Sunday television show to publicise his book, saying he was not inside the loop on these issues. Other top officials say they cannot recall meetings described by Mr Clarke.
And at the Independent Commission on terrorist attacks on the US yesterday and today, top Bush and Clinton administration officials are testifying on the issues involved. Mr Colin Powell insisted yesterday that terrorism has been the Bush administration's principal international preoccupation, while Ms Madeleine Albright said President Clinton also made it a top priority within the information and resources at their disposal. The pattern of attacks goes back to bombings of the World Trade Centre in 1993, through those on US embassies in Kenya and Sudan and on the USS Cole in Yemen in October 2000.
Mr Clarke's timing is well chosen to boost sales of his book and ensure his sensational reports reach a maximal audience. They go to the heart of the so-called war on terrorism proclaimed by the Bush administration and its portrayal of Mr Bush as a wartime president. The linkage between Iraq and al-Qaeda has been a central theme of his. This is despite the lack of real evidence to sustain it.
Mr Clarke's book is the latest insider account of the Bush administration to cast doubt on central tenets of its policy. Mr David Kay, the former chief arms inspector, says false claims about weapons of mass destruction in Iraq have damaged the international credibility of US intelligence. The former treasury secretary also says they were preoccupied with Iraq from their first days in office. Such claims could seriously weaken Mr Bush's position and have put him on the defensive against the Democratic candidate, Mr John Kerry.