WASHINGTON — The thought gnaws at Thomas J. Pickard: What would he have done differently if he had known about the far-flung terrorism leads his agents at the FBI were tracking from Phoenix to Minneapolis in the weeks before the Sept. 11 attacks?
"I go back and forth on that constantly," Pickard, the acting FBI director that summer, told the Sept. 11 commission last week. "It keeps me up at night, thinking: If I had that information, would I have had the intuitiveness to recognize, to go to the president, to do something different?"
In other words, if the government had responded more aggressively by better marshaling its intelligence, law-enforcement and defense resources that summer — just as intelligence warnings were reaching a fevered pitch — could the attacks have been prevented?
That question took on a powerful new resonance after the disclosure that President Bush received a detailed briefing less than five weeks before Sept. 11, 2001, about al-Qaida's intent to attack America, perhaps using hijacked planes.
In fact, many terrorism experts say, the administration had a large arsenal of options that might have helped disrupt the plot. A redoubled effort by the CIA and the FBI might have found evidence in their own files about the threat of terrorist pilots and about 2 of the 19 terrorists who would take part in the Sept. 11 plot, some terrorism experts suggest.
A heightened security presence at airports, including a public announcement that armed sky marshals would be randomly assigned to flights, might have forced the plotters to regroup or raised suspicions about the box cutters that some were believed to be carrying. And a review by the military could have developed a policy on whether to shoot down hijacked airliners.
"We had ample evidence that al-Qaida wanted to attack America, but we just stood by and waited for something to happen," said Charles Slepian, a specialist on aviation security who now heads a group called the Foreseeable Risk Analysis Center. "It was just another Tuesday in September, and it should not have been that way."
By the spring and early summer of 2001, U.S. intelligence officials were beginning to see worrisome and increasingly dire signs of terrorist activity. Intelligence reports disclosed last week by the Sept. 11 commission warned that "Bin Laden threats are real" and "Bin Laden planning high-profile attacks." George J. Tenet, the director of central intelligence, received a briefing paper that August titled "Islamic Extremist Learns to Fly" about the arrest days earlier in Minnesota of Zacarias Moussaoui. And an intelligence briefing that President Bush got at his ranch at Crawford, Texas, headlined "Bin Laden Determined to Strike in U.S," discussed the possibility of al-Qaida operatives hijacking planes.
Bush administration officials, under withering attack in recent weeks because of the new disclosures, say they did not have enough detailed information about the time, date or method of attack to stop the plot.
"Had I any inkling whatsoever that the people were going to fly airplanes into buildings," Bush said at a news conference last week, "we would have moved heaven and earth to save the country."
Indeed, some law enforcement officials say even if they had known about al-Qaida's intentions, there was little they could have done. They say that short of declaring martial law, the administration could not have risked public outrage by targeting Muslim men at airports. And they faced a murky threat with no specific site and time frame.
Michael Rollince, a senior counterterrorism official with the FBI, said the public and the news media were not fixated on the threat of terrorism before the Sept. 11 attacks. Citing the search for the two future hijackers living in San Diego — a search slowed by miscommunication between the CIA and the FBI — he asked, "Would CNN have really aired their photos if we'd asked them?"
The national security adviser, Condoleezza Rice, said the White House was "at battle stations" that summer because of the increased warnings. But many of the FBI's field agents said word of the heightened concerns never reached them, and top federal transportation and aviation officials were never notified to be on heightened alert for an attack.
An FBI agent in the field that summer who spoke on condition of anonymity said that while there were vague rumblings about terrorist concerns, it did not seem like an overriding priority. If it had, the agent said: "You'd cancel vacations. You'd watch the infrastructure. You'd beef up security at airports and ports and beef up the park service to make sure no one was sneaking around Mount Rushmore. That didn't happen."
Thomas H. Kean, the chairman of the Sept. 11 commission, said he was particularly troubled that word of Moussaoui's arrest — after officials at a flight school he attended noticed his suspicious behavior — never reached senior FBI officials.
"If it had," he said at last week's hearing, "maybe there would have been some action taken and things could have been different."
On a practical level, the White House would probably not have had time after Bush's Aug. 6 briefing to undertake many of the more severe aviation security steps initiated after the Sept. 11 attacks: like hiring and training thousands of federal air marshals, fortifying cockpit doors or installing massive luggage X-ray machines.
But experts say more moderate steps, like placing additional law enforcement and screeners at airports, were reasonable. What critics assert was lacking after the Aug. 6 briefing was any sense of urgency from the White House in response to the increased warnings. "If the White House would have made this a priority for the CIA and the FBI," said Richard Ben-Veniste, a Democratic member of the Sept. 11 commission, "and the defense secretary told them to 'get me every piece of information you have on the threat of hijackings in the U.S.,' what might have happened?"