Sea-based national missile defense systems have become the most discussed and least understood of all proposed missile defense projects. Proponents assert that Aegis destroyers and cruisers can quickly and inexpensively provide a highly-effective defense against both intermediate- and intercontinental-range ballistic missiles. In fact, sea-based national defense systems face major technological uncertainties, cannot be deployed for at least a decade and could prove prohibitively expensive.

A new article, "Lost at Sea," by Joseph Cirincione in the authoritative trade publication, Inside Missile Defense, details these problems.

Citing government reports over the last two years, Cirincione says sea-based defense "remains high-risk." And despite increased funding, its schedule has slipped steadily.

For example, citing a May GAO report, Cirincione says that the Navy will not begin operational testing until 2010, even though by then 50 percent of the required 80 missiles would be produced and delivered in 2008, and 100 percent by 2010.

"Such high concurrency essentially guarantees that the system will have cost overruns, schedule delays, and deploy substandard system elements," he writes. "By siphoning off defense dollars and ship assets for a system that, at best, will deliver only marginal military benefits, the pursuit of national missile defense schemes at sea will cause real harm to our national defense."

Cirincione disagrees with proponents who say retrofitting Aegis ships to incorporate new missile interceptors mission is as easy as adding a room to a house. Rather, it is more like "replacing your oil burner with a nuclear reactor," he writes.

Major questions remain, he says, about the ability of the LEAP interceptor and SPY radar to distinguish warheads from debris and decoys and whether LEAP can provide the lethality to destroy intended targets.

Additionally, "the operational requirements for sea-based, boost-phase missile defense would be formidable, perhaps overwhelming," he writes. With only 180 seconds between the time a hostile launch is detected and an interceptor must be launched, sailors would have to stay on constant alert. This raises serious questions about whether "this extremely rapid reaction mode could be sustained even for weeks during a crisis."