At 5:45 a.m. on September 11, Mohamed Atta and Abdulaziz Alomari passed their bags through an X-ray machine at the Portland International Jetport in Maine. A surveillance video camera recorded their faces for posterity. Atta, a man believed to have links to Osama bin Laden's terrorist network, walked calmly, wearing a blue dress shirt and dark pants. Alomari, in a white shirt and khakis, clutched a black bag, checking its contents. Three hours later, they and three other hijackers on American Airlines Flight 11 crashed a jetliner into the north tower of New York City's World Trade Center.
The attack might have been prevented had the surveillance system in Portland included a computerized face-recognition system. Atta's visage could have been matched to police databases and immigration watch lists that would have shown he was traveling in the United States on an expired visa, and that a warrant had been issued for his arrest. Security agents would then have taken Atta into custody, perhaps changing the course of history.
The tragic events of September 11 represent such an obvious failure of existing intelligence networks and airport security that many technologies once considered experimental or extravagant may now move onto center stage in the war against terrorism. These technologies include public surveillance systems, unmanned aircraft that will help hunt down terrorists in remote places, and computer software designed to decipher the secret communications between terrorists.
The United States is in a war unlike any it has fought before, a so-called asymmetric war in which the enemy avoids head-to-head confrontation with the nation's strengths, and targets its vulnerabilities. It means the front line, on any given day, could be anywhere. This war will be fought in the shadows against a near-invisible enemy.
Some names are known, of course. Osama bin Laden and his al-Qaeda network are prime targets. They have camps in Afghanistan but operate in many other countries in hard-to-penetrate cells. Finding these elusive foes and attacking them in a timely manner is the challenge faced by military and security forces. The war against terrorism will be fought not just on faraway battlefields, but also at home and in cyberspace.