The government has been distracted by fighting terrorism abroad to the point that the country is "not as safe as we ought to be," said Thomas Kean, the president of the now-disbanded 9/11 Commission.
"Some of the failures are shocking. Four years after 9/11, it is a scandal that police and firefighters in large cities still can't talk to each other when they are hit with a major crisis," Mr Kean said.
"It's scandalous that airline passengers are still not screened against all names on a terrorist watch list. It is scandalous that we still allocate scarce homeland security dollars on the basis of pork barrel spending and not on risk," he said.
Mr Kean was speaking at the release Monday of a report assessing the government's followup on the recommendations made by the commission, which published a 500-page report in July 2004 on the circumstances surrounding the September 11, 2001 attacks.
The newest report was severely critical of the administration of President George W Bush for paying too little attention to domestic security needs.
"Our leadership has been distracted in this country," said Mr Kean, the former governor of New Jersey.
"The United States are safer, but we're not as safe as we ought to be."
The report was also tough on Congress for making domestic security spending choices based not on crucial needs but on political favoritism.
A leader of the opposition Democrats wasted little time in chastising the government for security deficiencies.
"The report shows that while the administration and Congress are focused on fighting an offensive war in Iraq, they are dangerously neglecting the defensive war on terror we should be fighting here at home," said Senator Charles Schumer.
Another former member of the 9/11 Commission, Richard Ben-Veniste, spoke of the risk the free-hand given to the US military poses to individual liberties.
"America must be prepared to defend its values and its liberties as well as its homeland," he said.
The ex-commissioners assessed the government's response to 41 recommendations they made in the original 2004 report. On 18 points it gave the government a failing grade, delivering an especially harsh judgement on the government's treatment of detained suspected terrorists.
"US treatment of detainees has elicited broad criticism, and makes it harder to build the necessary alliances to cooperation effectively with partners in a global war on terror," they said.