The New Nuclear Threat.

• Author: VILBIG, PETER

AMERICA'S SPACE-AGE MISSILE DEFENSE SOUNDS LIKE SOMETHING OUT OF STAR WARS, WILL IT MAKE THE WORLD SAFER--OR WILL IT SET OFF A NEW ARMS RACE?

An American missile tipped with a dummy warhead roars out of its silo on the California coast. Seconds later, another missile from a U.S. base 4,300 miles away in the Pacific Ocean streaks into the clear January sky. At the nose of this interceptor lies what may be the world's most sophisticated high-tech gadget, a 120-pound kill vehicle designed to seek out nuclear warheads aimed at the U.S. and knock them to pieces.

From a bomb-proof command center deep inside a Colorado mountain, military technicians track this search-and-destroy test of an antimissile defense system with a series of radars and space satellites. The scene on the monitors looks like something out of Star Wars.

5 ... 4 ... 3 ...

High-tech sensors on the interceptor, chilled to -300 degrees in the cold of outer space, home in on the dummy warhead at 15,000 miles per hour. Seconds before contact, the command center is on the verge of celebration. Suddenly, the interceptor veers--and misses. The dummy warhead plummets into an empty stretch of the Pacific Ocean.

Welcome to the new arms race, 21st-century style. This failed test is just the latest snag in an ambitious $60 billion American plan to create a network of missile interceptors that would form a defensive shield against nuclear attacks from other countries.

After years on the back burner, the threat of nuclear missiles has suddenly become a major concern again. So-called "rogue nations"--countries such as Iran, Iraq, and North Korea, that ignore international law and are sworn enemies of the U.S.--are busily trying to build nuclear warheads and the sophisticated missiles needed to launch them at America.

In response, the U.S. has begun testing interceptors, and if President Clinton gives the go-ahead this fall, the first 25 of them, stationed in Alaska, could come on-line in five years. Polls show that Americans back the idea of a missile defense system by a wide margin. But the plan raises a host of difficult questions: Will it escalate the arms race? How safe is safe enough? And, given test results like the one in January, will it work?

WASN'T THE THREAT OVER?

We aren't supposed to be living in fear of nuclear attack anymore. The nuclear age began in 1945, when the U.S. dropped atomic bombs on two Japanese cities to hasten the end of World War II. The Soviet Union developed its own bomb in 1949, and the two nations...