Al-Qaeda's death has long been heralded. In recent months, a succession of Bush administration figures, the director of the CIA and other senior intelligence officials, academics and pundits have proclaimed if not the movement's imminent demise, than the definitive beginning of its end. The inadvertent result is an illusion of security recently reflected in nation-wide polls that show terrorism at the bottom of voters' concerns in 2008-a dramatic change from the last presidential election. But, if we believe we are safe, we may face the most consequential terrorist attack yet.

On September 11 2001, nineteen terrorists hijacked four airplanes and changed the course of history. In the years since, al-Qaeda has shown itself to be among the world's most formidable and resilient terrorist movements. The full weight of the U.S.-led war on terrorism, declared by President George W. Bush following the September 11 attacks, has been directed against the movement. Yet, despite its expulsion from Afghanistan-and the loss of its training camps, operational bases and command headquarters in that country-as well as the deaths of thousands of its fighters and the killing or capture of many of its leaders, al-Qaeda has demonstrated a remarkable ability to survive in the face of this concerted onslaught and carry on its violent campaign. Despite the comparatively far more modest amenities and confining nature of Pakistan's Federally Administered Tribal Areas (FATA) and surrounding provinces, al-Qaeda has nonetheless been able to reconstitute its global terrorist reach.

Indeed, 2008 marks the twentieth anniversary of al-Qaeda's founding. The movement thus joins a select group of terrorist organizations that have survived at least two decades or more. Such groups are often the most consequential and pose the greatest terrorist threats. They are learning organizations that have adapted and adjusted to even the most formidable governmental countermeasures. They are capable of planning and executing operations as well as identifying and building a long-term strategy. They are equally adept at gathering intelligence and conducting surveillance without detection. They are implacable with a steely determination that is difficult to diminish, much less defeat. Who could have foreseen in 1988 where al-Qaeda would be today? It has survived the onslaught directed against it as part of the global war on terrorism led by the United States, the world's remaining superpower. It has rebounded from the setback and loss of Afghanistan in 2001 achieved by an unprecedented international coalition that was mobilized against terrorism as a result of the September 11 2001 attacks. Al-Qaeda today is among the globe's most universally recognized and best known "brands." Its founder and leader is a source of inspiration, emulation, and empowerment. Finally, al-Qaeda and bin Laden can credibly, however ignominiously, claim to have changed the course of history. It is precisely this sense of historical inevitably and catharsis that fuels and sustains bin Laden and the movement he founded today.

Whatever the future holds for Osama bin Laden and al-Qaeda, it is indisputable that they have had a seismic effect on the United States and the entire world. And, in this respect, the epic battle that he launched is not over yet. Indeed, a terrorist group like al-Qaeda that has now survived two decades evidences the determination, resilience, and ability to overcome or obviate even the most consequential countermeasures of its governmental adversaries. In this respect, the movement doubtless continues to pin its hopes and faith on some new, spectacular terrorist attack that will catapult al-Qaeda back into prominence and re-direct them back onto an upward trajectory. It is exactly when we are lulled into complacency and our defenses are down, that al-Qaeda will strike.

Bruce Hoffman is a professor at Georgetown University's School of Foreign Service and a senior fellow at the U.S. Military Academy's Combating Terrorism Center, West Point, NY. The second edition of his book, Inside Terrorism, was published in 2006. He is also a contributing editor at The National Interest.