There. It was as if a dam had broken. Within hours other officials and experts followed. Tom Ridge, President George W. Bush’s director of Homeland Security, contradicted his previous week’s reassurance of the amateurish quality of the pathogen sent to Daschle, admitting that terrorists “intended to use this anthrax as a weapon.” Sheepish scientists conceded that, while they might know a lot about bacteriology, they’d known next to nothing about how mail is handled (shaken, pounded and compressed) or what size envelope pores are. The not-ready-for-prime-time performance was obvious to the public. In the new NEWSWEEK Poll, only 48 percent of Americans give the administration credit for having a good plan to combat bio- and other terrorist threats at home. Only 43 percent say the administration has been giving people as much reliable information on anthrax attacks as they need. And half take the view that the Bush team is either not releasing the right information because they don’t know themselves, or are purposely holding back to avoid panicking the public.

The administration’s new tone reflects reality: life comes with risks, and life after the Twin Towers collapsed and anthrax began traveling the mails probably comes with more. But what risks do we have to worry about? Americans have never been good at knowing that: when asked, many say there is a greater chance of dying from living near a Superfund site than there is from driving a car, although by numbers the risk of the latter is many times the former. Now, after Sept. 11, getting the risks right might be a matter of thousands of lives and billions of dollars, not to mention the difference between chronic anxiety and realistic prudence.

In the chapters that follow, NEWSWEEK describes what steps experts at every level of government–from the Office of Homeland Security to local police departments–as well as in the private sector are taking or contemplating to secure America’s points of vulnerability. Some changes were well underway before Sept. 11; others have still barely begun. Some are steps we know how to implement, and that require only will and determination–qualities that America has in abundance, at least for now. Others require technologies, or ways of acting, or chains of responsibility, that we have yet to master. Some steps will necessitate changes in how we live, such as no backpacks at sporting events. Others will remainso far behind the scenes as to be invisible to most of us, such as installing high-density particle filters in ventilation systems.

Our aim is not unrealistic reassurance. “The right answer to the question ‘Can you assure me that X is safe?’ is always no,” says risk consultant Peter Sandman. What we hope to do is convey the smartest assessments of the size of the risks and describe what is being done to reduce them. Nor is our aim to give terrorists a road map to our points of vulnerability. Recent Homeland Defense reports–from panels led by Gov. James Gilmore, by former senators Gary Hart and Warren Rudman, by former ambassador Paul Bremmer, among others–have probed these vulnerabilities. A central tenet of counterterrorism is that, to defend yourself, you must identify the targets that need defending. As President Bush has made clear, “you” means not only elected officials and emergency-response teams, but each and every American. Here, then, is what we all need to know.