While dirty bombs and bioweapons steal headlines, the Pentagon is plowing ahead with a 21-year-old plan to silence a more traditional weapon of mass destruction: the intercontinental ballistic missile. Despite widespread criticism, this summer the Missile Defense Agency will deploy the humble beginnings of a nationwide missile defense shield.

If all goes according to plan, by September the rudimentary shield will consist of 10 ground-based interceptors (six in Alaska and four in California) and a constellation of early-warning infrared and radar systems. The interceptors are designed to collide in orbit with long-range ballistic missiles, presumably launched by North Korea or China, and annihilate them upon impact. At least that’s the plan on paper. Unlike other U.S. weapons systems, which must pass a series of benchmark tests before deployment, the system remains largely untested. (The testing requirements were quietly waived in 2002 to enable the MDA to meet a president-mandated fall 2004 deadline.)

Critics say the system, which will cost upwards of $53 billion over the next five years, is too premature for deployment. “The fundamental problem is that there’s no way to reliably discriminate between a decoy and a real warhead,” says MIT nuclear physicist Theodore Postol. Despite more than two decades of research, “the basic science just isn’t there,” he says. And even if the Pentagon could employ a perfect missile defense system, opponents argue that it would do little to protect the United States from an ever-growing network of terrorists who hardly need ICBMs to threaten homeland security. “I’m no hippie,” Postol says. “I like weapons that work.”

Reporting by Mark Farmer