The United States recently followed Israel's claims that it was ready to shoot down any nuclear missile aimed its way, with similar claims of its own.  The U.S. has begun reexamining space-based defenses and has also been quietly upgrading its ground-based missile-defense shield, even as U.S. President Barack Obama pushes his vision of global nuclear disarmament.

A new study, though, published in the Bulletin of Atomic Scientists, insists that the U.S.'s claims of security are very flawed.  Authored by two top American security authorities, the study argues that despite recent upgrades and breakthroughs, America assertion that its homeland is safe from any airborne nuclear threat is a "dangerous fantasy".

George N. Lewis, a physicist and associate director of the Peace Studies Program at Cornell University, and Theodore A. Postal, a physicist and professor of science, technology, and national security policy at MIT, authored the new report.

The report specifically targets an April 2010 U.S. government resolution that declared the U.S. to be safe from ballistic missile threats from hostile nations such as Iran and North Korea, thanks to its US Ground-Based Missile Defense (GMD) and Standard Missile 3 (SM-3) systems.  According to Professors Lewis and Postal, though, this new declaration is based on a "technical myth" as Iran is thought to be developing countermeasures to make its ballistic devices harder to shoot down.  Other hostile nations may be working on similar countermeasures.

But the pair of professors isn't just griping about what they view as an ineffective strategy -- they're proposing what seems like a sensible solution.  They advise that rather than rely on what they call a "ineffective, untested, and unworkable" GMD system, that funding instead be put into developing a constantly airborne fleet of stealth drones over the airspace of hostile nations.

That way, rather than trying to shoot down missiles that have already reached the United States, Northern and Western Europe, and Northern Russia -- and likely are deploying countermeasures -- the drones would instead launch fast interceptors taking out the missiles over the hostile country's own airspace, preventing them from deploying effective countermeasures.

The plan would also be kosher with the New START arms reduction treaty, recently signed by U.S. President Barack Obama and Russian President Dmitry Medvedev.  That treaty set a limit of 1,550 ready-to-use ballistic warheads (each) on the U.S. and Russia's respective arsenals.  It also contained language limiting certain missile defense strategies.

The current systems, according to the pair of researchers, are ineffective for two reason.  The first is simple physics.  Interceptors, in their current form, can only accurately predict and target regular trajectories from finned missile designs.  Iran is reportedly designing fin-less designs that would likely cause interceptors to miss.  They could also employ tumbling missile designs, similar to those used to defeat the Patriot Missile Defense in the Gulf War of 1991.

Secondly, decoys can also hinder proper shoot-down.  U.S. and Russian ballistic missiles are equipped with decoy warheads, so that once in space, the real warhead launches amid a swarm of identical dummy warheads, making interception an increasingly impossible task. There's no reason why Iran, North Korea, or others would be unable to develop similar technology.

The authors take special issue with the U.S. Defense Department's claims that the U.S. is already defended from nuclear threats, pointing out that they have no evidence supporting that the system would work in combat.  Professor Lewis comments, "These claims are fantastical, audacious, and dangerous."

A drone solution they say would provide a full answer to the problem and would not require new technology.  Further, shot down warheads would fall on enemy territory should they still manage to activate after being hit by an interceptor.

Professor Lewis concludes, "The situation is urgent, as Iran is already demonstrating countermeasures in flight tests that would render both the GMD and SM-3 long-range missile defense systems ineffective.  If we, as a nation, refuse to confront the fact that our chosen defense system is not reliable, and if we fail to build a robust and reliable alternative system using existing technology, we will have only ourselves to blame if the continental United States suffers a catastrophe as a result of the successful delivery of a nuclear weapon by long-range ballistic missile."