CDI's analysis of the CBO report determined that annual costs are expected to rise to $18 billion by 2016.

Philip Coyle, a CDI senior adviser and director of operational test and evaluation for the Office of the Secretary of Defense from 1994-2001, told United Press International that "costs for missile defense might even keep going up (beyond the CBO estimates)."

While Coyle supports missile defense research, he has concerns about the effectiveness of some of the programs currently in development.

"I do support defense research and research in missile defense, but the issue is that some of these systems have no demonstrated capability to defend the United States in normal conditions," he said.

Until such capability is demonstrated, Coyle wonders if the $18 billion shouldn't be dedicated to more practical programs.

"Missile defense is very expensive -- in fact, it is the single most expensive program in the Department of Defense. And we haven't seen anything yet, and yet the costs will continue to climb," he said.

However, Baker Spring, a fellow at the Heritage Foundation who specializes in national security policy, said it was a mistake to read too much into the CBO estimates.

"Whether the $18 billion figure is accurate in the long-term is a bit speculative; some programs may fall out, some may be stretched, and some may be accelerated," he said.

Spring faulted the Department of Defense for not making a stronger commitment to U.S. missile defense development over the past 25 years.

"If we had pursued missile defense at the margins for all these years, we wouldn't need the spike that is referred to in the CBO report," he said.

Spring said he believed that increased spending on missile defense development was a good thing for U.S. national security and foreign policy. He said he did not share Coyle's concerns about the potential of overspending on missile defense when many programs don't yet have a demonstrated capability.

"If we took Dr. Coyle's approach, we would be accepting a 'mutually assured destruction' relationship with North Korea, Iran, China and even Russia, and why would we want that?" he asked.

Spring said he believed that an effective missile defense program could prevent an arms race from occurring in East Asia in the wake of North Korea's nuclear test. Instead of developing nuclear weapons themselves, an effective missile defense program could persuade countries like South Korea and Japan to rely on the United States as their primary line of defense against North Korean aggression, he said.

"I believe the Japanese believe that missile defense is an effective tool," he said.

Coyle, however, cited other national security threats that even the most effective missile defense program will be unable to do anything about.

"By 2016, we will be spending twice as much on missile defense as we do on the entire U.S. Coast Guard. And unfortunately, missile defense isn't effective against car bombs or IEDs or weapons of mass destruction smuggled in cargo," he said.

The ambitious ballistic missile defense program energetically pushed by the Bush administration and by the Republican-controlled U.S. House of Representatives over the past six years is designed to develop a BMD capability to shoot down nuclear-armed intercontinental ballistic missiles launched by so-called rogue nations such as North Korea and Iran.

It may also be effective against missiles launched by China. However, it is not designed to defend the United States against missiles launched with multiple independently-targeted vehicle, or MIRV capabilities, like many of the thousands of missile's in the Russian Strategic Rocket Forces.

So far, U.S. BMD interceptors have not been successfully tested against target missiles employing decoy technologies now widely used on both Russian and Chinese ICBMs.

Related Links
Center for Defense Information
Learn about missile defense at SpaceWar.com