The assassination of opposition leader Benazir Bhutto, the defiance of militants and public unease with President Pervez Musharraf’s government have raised questions about the stability of Pakistan and the security of its nuclear armament. Exacerbating these concerns is a nervous neighbor. In January, weeks after an Indian missile successfully crashed into another missile over the Bay of Bengal, an official announced that India could deploy a defense shield against ballistic missiles by 2011.

By seeking to fend off its tenacious rival, India may have inadvertently increased the risk of a regional nuclear exchange. Furthermore, “missile defense will make it likely that greater damage will be inflicted on India” if such a war breaks out, argues Theodore Postol, a defense analyst at the Massachusetts Institute of Technology.

Experts have long considered the Indian subcontinent to be the likeliest flash point for the world’s first nuclear exchange [see “India, Pakistan and the Bomb,” by M. V. Ramana and A. H. Nayyar; Scientific American, December 2001]. Ever since India began the nuclear arms race in 1974, Pakistan has responded tit-for-tat to every development. The effort seems to have paid off for Pakistan: in 1999, when it sent paramilitary forces across the border, India repelled the attackers but did not pursue them home, reportedly because of threats of atomic retaliation.

India’s planners have now decided that a missile defense shield is the answer to their self-inflicted predicament. They have an ally in the Bush administration, which last year forged a deal that will allow India to purchase uranium from international sources for its civilian reactors. If the agreement goes through, India will be able to process all its domestic uranium for the military, adding 60 to 100 kilograms of weapons-grade plutonium annually to its current stock (estimated at 600 kilograms). Earlier, in 2005, the U.S. had offered to share military technology, including that of missile defense, with India. Officials and military contractors from around the world have since been thronging to New Delhi in the hope of selling components of a defense system.

Many scientists have pointed out the inherent shortcomings of ballistic-missile defense [see “Holes in the Missile Shield,” by Richard L. Garwin; Scientific American, November 2004]. Defense systems of this kind cannot, for instance, distinguish decoys from real threats. In South Asia, short distances magnify the problems. “It’s pretty unlikely that you can expect to reliably intercept anything,” opines physicist Zia Mian of Princeton University, who studies nuclear proliferation and global security. India’s Defense Research and Development Organization claims that its planned defense shield will destroy an enemy missile three minutes after the missile’s detection by radar.

Early-warning radar, such as one that India has imported from Israel, could detect the missile and determine its course within 110 seconds after its launch. But a ballistic missile launched on a low trajectory from, say, a Pakistani air base could reach New Delhi in as little as five minutes, according to Mian and physicists M. V. Ramana of the Center for Interdisciplinary Studies in Environment and Development in Bangalore and R. Rajaraman of Jawahar­lal Nehru University in Delhi.

That could leave technicians with too little time to figure out if the warning is real. U.S. scientists once spent eight minutes determining that a warning of a Soviet launch was false. Indeed, false alarms are frequent when it comes to early-warning systems. A flight of geese or an incidence of atmospheric turbulence can fool radar, and anomalous reflections of the sun can trick satellite-based infrared detectors. Between 1977 and 1988—the only period for which data have been released—the U.S. recorded an annual average of 2,600 false alarms of ballistic-missile launches from the Soviet Union. Even if India responds to a false alarm just by launching an interceptor missile, that action could be interpreted by Pakistan as an attack.

Moreover, soon after India acquired early-warning radar Pakistan tested a cruise missile, which Postol believes was reverse-engineered from an American Tomahawk missile that fell in Pakistan during a 1999 attack on terrorist training camps in Afghanistan. Powered throughout its flight, such a missile can hug the ground to evade radar. And in an apparent response to the India-U.S. nuclear deal, Pakistan has begun building a reactor for producing plutonium, which may yield a warhead small enough to fit onto a cruise missile. Pakistan also possesses ballistic missiles fitted with small fins on their forward, payload sections. These structures can add maneuverability, making the warheads exceedingly difficult to catch.

Still, “the attacker is always concerned that missile defense might work better than he thinks,” Postol points out, and will launch more projectiles than necessary to ensure that at least a few get through. He suggests an alternative way of avoiding a nuclear holocaust. Both nations should disperse and hide their missiles and authorize a designated general in a remote outpost to launch retaliatory strikes should the political leadership be taken out in a first strike—and let the other side know. That way the rulers of both countries can be sure that a nuclear misadventure will lead to their homeland becoming history. Unlike missile defense, mutually assured destruction is at least a time-tested way to keep nuclear weapons in their holsters.