Thousands of shoulder-fired weapons are unaccounted for, intensifying a search for ways to reduce terror threat to jets.
Missile defense proponents defend their program against critics who argue that it is unworkable and unnecessary in the global war against terrorists who are unlikely to use ballistic missiles.
New research shows how easily livestock and crops could be hit by 'agroterrorists.'
The U.S. is actively rethinking the role of its arsenal of weapons of mass destruction. Issues under consideration include: the resumption of nuclear testing, ambivalence over controlling chemical and biological weapons, and the development of new "bunker busting" nuclear weapons.
Russian use of chemical weapons in a recent hostage crisis and the announcement that the U.S. is investigating new substances that can be used to disable terrorists has forced chemical and biological weapons back on to the world agenda.
Today, as the United States bombs terrorist sites and other targets in Afghanistan, the prospect of a nuclear terrorist attack looms larger as a domestic security concern. The likelihood of such an attack, government officials and experts say, may be small - but the possible consequences are too horrific to ignore.
Many experts say the United States is increasingly vulnerable to a bioterrorist attack, particularly given the sophistication shown by terrorists last week.