Time to revive debate about space-based missile defense.

• Author: Schaffer, Marvin Baker

Boost phase missile defense is necessary to reliably and cost-effectively defeat the most advanced intercontinental ballistic missile threats, those of the Russian Federation and the People's Republic of China.

Current intercontinental ballistic missile (ICBM) defenses do not have the necessary ability to engage the most sophisticated configurations that have been and can be deployed by the Russians and to a lesser extent by the Chinese.

Specifically, U.S. defenses cannot successfully engage ICBMs containing multiply independent reentry vehicles (MIRVs), extensive sophisticated decoys or maneuvering reentry vehicle capability.

Russian missile forces include several thousand ICBMs, and China has 50 to 75. Both countries are in the process of modernizing their forces, and, ominously, by 2020 many of the systems are expected to carry nuclear-tipped MIRVs and sophisticated decoys.

The Russians also have hundreds of submarine-launched ballistic missiles and the Chinese may have dozens.

Although Iranian and North Korean forces are presently not as threatening as Russian and Chinese forces, both may also stockpile sophisticated nuclear ICBMs within a decade. Their missiles currently are non-nuclear and have only intermediate range capability threatening nearby U.S. allies. Other entities or non-state groups could acquire nuclear-tipped ballistic missile weapons as well if unimpeded. Hezbollah in Lebanon, a client of Iran, fits this category.

One configuration to redress this threat is called "brilliant pebbles." It requires putting 300 to 1,000 spacecraft into low-Earth orbit at an overall cost of roughly $1 billion. That will enable defense in the boost phase to preempt use of M1RVs and other sophisticated countermeasure techniques.

Another defensive technique is the use of standoff remotely piloted aircraft such as the Air Force's MQ-9 Reaper. They could Fire air-to-air missiles at ICBMs that are still in the boost phase. The initial procurement costs would be at least 17 times that of brilliant pebbles, but it would not require placing objects into space and the drones would be recoverable.

A third technique could employ high-energy solid-state lasers deployed in large numbers and placed in low-Earth orbit. This would cost at least 100 times more than brilliant pebbles.

Both the brilliant pebbles and RPV approaches warrant further research and development.

A raging political controversy began in 1972 when the Anti-Ballistic Missile Treaty was...