The al Qaeda terrorist network posed a threat to the United States for almost a decade before the attacks of Sept. 11, 2001. Throughout that period -- during the eight years of the Clinton administration and the first eight months of the Bush administration prior to Sept. 11 -- the U.S. government worked hard to counter the al Qaeda threat.

During the transition, President-elect Bush's national security team was briefed on the Clinton administration's efforts to deal with al Qaeda. The seriousness of the threat was well understood by the president and his national security principals. In response to my request for a presidential initiative, the counterterrorism team, which we had held over from the Clinton administration, suggested several ideas, some of which had been around since 1998 but had not been adopted. No al Qaeda plan was turned over to the new administration.

We adopted several of these ideas. We committed more funding to counterterrorism and intelligence efforts. We increased efforts to go after al Qaeda's finances. We increased American support for anti-terror activities in Uzbekistan.

We pushed hard to arm the Predator unmanned aerial vehicle so we could target terrorists with greater precision. But the Predator was designed to conduct surveillance, not carry weapons. Arming it presented many technical challenges and required extensive testing. Military and intelligence officials agreed that the armed Predator was simply not ready for deployment before the fall of 2001. In any case, the Predator was not a silver bullet that could have destroyed al Qaeda or stopped Sept. 11.

We also considered a modest spring 2001 increase in funding for the Northern Alliance. At that time, the Northern Alliance was clearly not going to sweep across Afghanistan and dispose of al Qaeda. It had been battered by defeat and held less than 10 percent of the country. Only the addition of American air power, with U.S. special forces and intelligence officers on the ground, allowed the Northern Alliance its historic military advances in late 2001. We folded this idea into our broader strategy of arming tribes throughout Afghanistan to defeat the Taliban.

Let us be clear. Even their most ardent advocates did not contend that these ideas, even taken together, would have destroyed al Qaeda. We judged that the collection of ideas presented to us were insufficient for the strategy President Bush sought. The president wanted more than a laundry list of ideas simply to contain al Qaeda or "roll back" the threat. Once in office, we quickly began crafting a comprehensive new strategy to "eliminate" the al Qaeda network. The president wanted more than occasional, retaliatory cruise missile strikes. He told me he was "tired of swatting flies."

Through the spring and summer of 2001, the national security team developed a strategy to eliminate al Qaeda -- which was expected to take years. Our strategy marshaled all elements of national power to take down the network, not just respond to individual attacks with law enforcement measures. Our plan called for military options to attack al Qaeda and Taliban leadership, ground forces and other targets -- taking the fight to the enemy where he lived. It focused on the crucial link between al Qaeda and the Taliban. We would attempt to compel the Taliban to stop giving al Qaeda sanctuary -- and if it refused, we would have sufficient military options to remove the Taliban regime. The strategy focused on the key role of Pakistan in this effort and the need to get Pakistan to drop its support of the Taliban. This became the first major foreign-policy strategy document of the Bush administration - - not Iraq, not the ABM Treaty, but eliminating al Qaeda.

Before Sept. 11, we closely monitored threats to our nation. President Bush revived the practice of meeting with the director of the CIA every day -- meetings that I attended. And I personally met with George Tenet regularly and frequently reviewed aspects of the counterterror effort.

Through the summer increasing intelligence "chatter" focused almost exclusively on potential attacks overseas. Nonetheless, we asked for any indication of domestic threats and directed our counterterrorism team to coordinate with domestic agencies to adopt protective measures. The FBI and the Federal Aviation Administration alerted airlines, airports and local authorities, warning of potential attacks on Americans.

Despite what some have suggested, we received no intelligence that terrorists were preparing to attack the homeland using airplanes as missiles, though some analysts speculated that terrorists might hijack airplanes to try to free U.S.-held terrorists. The FAA even issued a warning to airlines and aviation security personnel that "the potential for a terrorist operation, such as an airline hijacking to free terrorists incarcerated in the United States, remains a concern."

We now know that the real threat had been in the United States since at least 1999. The plot to attack New York and Washington had been hatching for nearly two years. According to the FBI, by June 2001 16 of the 19 hijackers were already here. Even if we had known exactly where Osama bin Laden was, and the armed Predator had been available to strike him, the Sept. 11 hijackers almost certainly would have carried out their plan. So, too, if the Northern Alliance had somehow managed to topple the Taliban, the Sept. 11 hijackers were here in America -- not in Afghanistan.

President Bush has acted swiftly to unify and streamline our efforts to secure the American homeland. He has transformed the FBI into an agency dedicated to catching terrorists and preventing future attacks. The president and Congress, through the USA Patriot Act, have broken down the legal and bureaucratic walls that prior to Sept. 11 hampered intelligence and law enforcement agencies from collecting and sharing vital threat information. Those who now argue for rolling back the Patriot Act's changes invite us to forget the important lesson we learned on Sept. 11.

In the immediate aftermath of the attacks, the president, like all Americans, wanted to know who was responsible. It would have been irresponsible not to ask a question about all possible links, including to Iraq -- a nation that had supported terrorism and had tried to kill a former president. Once advised that there was no evidence that Iraq was responsible for Sept. 11, the president told his National Security Council on Sept. 17 that Iraq was not on the agenda and that the initial U.S. response to Sept. 11 would be to target al Qaeda and the Taliban in Afghanistan.

Because of President Bush's vision and leadership, our nation is safer. We have won battles in the war on terror, but the war is far from over. However long it takes, this great nation will prevail.

The writer is the national security adviser.