The 9/11 commission report that has captured the nation's attention provides the most recent warning that al-Qaida terrorists are intent on attacking again — and on using chemical or biological weapons to increase their deadly force. But how ready is the United States to defend itself against that danger, and to respond if it actually happened?
Some security in Boston is visible, like the eight-foot-high fence around the Democratic convention site.
But precautions against biological and chemical attacks are not easily seen — like the tons of vaccines shipped to Boston and other cities this month; or the highly sensitive equipment to detect traces of poisons in the air that is now in Boston and 30 other cities, covering 240 million Americans.
Just this week, President George W. Bush signed a law giving the nation's drug companies more than $5 billion to develop antidotes to chemical and biological weapons.
That measure sailed through a Congress already sensitized to the threat by attacks with anthrax and ricin.
There's now wide agreement that the nation's chemical and biological defenses have come a long way.
"If we were on the one-yard line on September 11, I'd say we're probably on the 40- or 50-yard line now. We have made just outstanding progress," says Parney Albright of the Department of Homeland Security.
Homeland officials say they're now more aggressively monitoring the safety of the food supply with sensors — even beginning to spot check milk production and city water supplies for signs of an attack.
Monitors have also been installed in some subways to sniff out chemical weapons — with similar detectors at airports.
Cities are also conducting exercises to test their responses to chemical and biological attacks.
But public health experts say a huge problem remains — the lack of capacity at the nation's hospitals. They'd be overwhelmed by victims desperate for treatment.
"Most hospitals don't have decontamination capability on a broad scale. And they can't deal with the casualty care that would accompany any weapon of mass destruction, particularly a biologic or chemical event," says NBC News consultant and bioterrorism expert Dr. Sue Bailey.
It's one of the biggest problems — how to build extra capacity into the health care system to respond to terror attacks, at the same time the nation is trying to make health care cheaper.