The Unsheltering Sky

As test flights go, FTG-06b was a dazzling affair. The mission was part of a programme called Ground-based Midcourse Defence (GMD), which is supposed to provide America’s main shield against intercontinental ballistic missiles (ICBMs) with a range beyond 5,500km (3,418 miles). FTG-06b involved the launch (pictured opposite) on June 22nd from Vandenberg Air Force Base in California of a hypersonic interceptor. It successfully annihilated an unarmed warhead which had been fired into space from a US Army site on Kwajalein Atoll in the western Pacific Ocean.

The warhead was tracked by two American naval vessels: a destroyer equipped with an Aegis anti-missile system and a $900m floating offshore oil-rig, which had been kitted out with a highly sophisticated active phased-array X-band radar. Far more powerful than conventional radar, the X-band system can calculate—with the help of some big computers in Colorado Springs—the size, shape and trajectory of a baseball-sized object 4,000km away travelling at 32,000kph.

Twelve years ago the United States withdrew from the Anti-Ballistic Missile Treaty, a 1972 deal that limited the testing and deployment of anti-ICBM weapons by America, the former Soviet Union and, later, Russia and some ex-Soviet republics. Since then, most technological advances in such systems have been in America, where the Missile Defence Agency (MDA) has spent some $98 billion on various projects since 2002. Although China appears to be working on an anti-ICBM system, Russia is the only other country with such a programme—and it is far less capable, says Jeffrey Caton, a former US Air Force colonel and space-warfare specialist.

Meanwhile, the threat grows as potential attackers continue to acquire “more complex, survivable, reliable and accurate” ICBMs equipped with countermeasures, Vice-Admiral James Syring, the MDA’s boss, told Senate lawmakers in June. Next year Iran could have a ballistic missile able to reach America, he added. But others think that is at least several years away. North Korea is also testing rockets and satellite systems which could carry a nuclear warhead. Arun Prakash, a former chairman of India’s Chiefs of Staff Committee, sees the one-upmanship between offence and defence systems as “a ding-dong battle” with the defender at a perpetual disadvantage because it is far easier to build a missile than shoot it down.

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