Reporting from Kabul, Afghanistan, and Washington — Wherever there are Western troops in Afghanistan, the clatter-thump of helicopter rotors serves as the soundtrack. Choppers are the workhorses of this war, with hundreds of them moving soldiers and supplies daily across a rugged landscape.
Because of the NATO force's heavy reliance on them, one of the most eye-catching revelations in a trove of classified documents posted on the Internet this week was that insurgents apparently used a portable heat-seeking surface-to-air missile to shoot down a twin-rotor CH-47 Chinook in Helmand province in May 2007, killing seven Western service members.
If the Taliban and other insurgent groups possessed large numbers of these weapons, it could dramatically alter the dynamics of a war effort that already is struggling. Shoulder-launched missiles downed scores of Soviet helicopters in the 1980s, helping ragtag Afghan rebels prevail against a vastly superior force.
Most experts believe that the antiaircraft threat currently posed by the insurgents is relatively limited, and that they don't have significant stocks of surface-to-air missiles, at least for now.
The shooting down of choppers remains a relative rarity in the Afghan conflict, and heavy machine guns and rocket-propelled grenades are almost always found to have been used.
"After nine years, if they had a lot of them, we would have seen them by now," said a U.S. official who spoke on condition of anonymity because he was not authorized to speak about the subject on the record. Sporadic reports of attacks with surface-to-air missiles have often turned out to involve other weapons, the official said.
But portable surface-to-air missiles can be procured from many illicit sources in the region. Afghanistan's neighbors include Iran, Pakistan and China. NATO said this month that an intercepted memo from Taliban supreme leader Mullah Mohammed Omar suggested that the insurgents were redoubling efforts to obtain a variety of sophisticated armaments.
"It's wartime, and our warriors are searching for new weapons," said Taliban spokesman Zabiullah Mujahid, reached by telephone.
By their nature, shoulder-launched missiles — "manpads," in military parlance — are easily transportable, making them less difficult to smuggle than bulkier weapons systems. Mujahid declined to discuss any recent additions to the Taliban arsenal, but said, "It is difficult to stop weapons trafficking. The world's black market is open to us."
Matt Schroeder, an analyst with the Federation of American Scientists, said it is possible that there have been more attacks on coalition aircraft than have come to light. Yet Schroeder was skeptical that shoulder-fired missiles represented a major threat because such attacks in large numbers would be likely to come to public attention.
The downing of any aircraft is usually announced quickly by NATO's International Security Assistance Force. Two U.S. servicemen died last week when a helicopter was brought down by hostile fire in Afghanistan's south; the incident was disclosed by military officials within hours.
"It's hard to hide the loss of a lot of aircraft," Schroeder said.
Missiles being used by Afghan insurgents are generally thought to be of older Soviet and Chinese design, types that can be neutralized by common countermeasures such as diversionary flares.
The missiles are not easy to aim, and sometimes can be thrown off target even by sunlight and clouds. That could account for the fact that the classified documents posted by the organization WikiLeaks referred to at least 10 suspected missiles having missed their targets, according to an analysis by Britain's Guardian newspaper.
Taliban leaders have said the movement has a number of stored Stinger missiles left over from the period of Soviet occupation, which ended more than 20 years ago. The leaked documents suggested that some of them still might have been usable.
"The presumption had been that those systems that were distributed by the United States in the 1980s would be inoperable because their batteries would have run out," said Jeremy Binnie, a senior terrorism and insurgency analyst at IHS Jane's. "But [in the leaked documents] there are people reporting to have seen contrails like those left by a Stinger."
Lincoln P. Bloomfield Jr., who was appointed in 2008 by the George W. Bush administration to take the shoulder-fired missiles out of circulation, said there remains a real threat from the weapons in Afghanistan, as elsewhere.
"The U.S. and coalition troops in Afghanistan attract adversaries," he said. "This is among the elements in their playbook."
He said that even though older missiles may have been sitting in hot, dusty warehouses for years, "sometimes they still work."
Bloomfield said the U.S. government has destroyed about 28,000 of the weapons since 2002 through buyback programs and other efforts. As special envoy, he negotiated with governments to destroy the portable missiles in their arsenals, or at least to ensure that they were safe from theft.
On the black market, the missiles' cost ranges from a few hundred dollars to many thousands of dollars. But at least for some insurgent factions, money may not be much of an issue.
The German magazine Der Spiegel, which like the Guardian and the New York Times received advance access to the WikiLeaks documents, cited insurgent leader Gulbuddin Hekmatyar as exhorting followers to procure weapons, including surface-to-air missiles, to use against coalition forces.
"Attack him with Stinger missiles!" Hekmatyar told followers in Lowgar province in 2005, according to the magazine. "No matter the cost, $150,000 or $200,000, I will pay."