|FAS Public Interest Report
The Journal of the Federation of American Scientists
Volume 56, Number 3
FAS Home | Download PDF | PIR Archive
The Real Terrorist Missile Threat, and What Can be Done About ItBy Robert Sherman
The past year has seen intense speculation on why early signs of the World Trade Center attack were not detected. Historians will forever dispute whether the FBI was negligent in failing to recognize that something consequential was in the offing as Arab students with poor flying skills asked to learn how to fly jumbo jets without learning how to take off or land.
But today the civilized world faces a threat many times more serious than 9-11. The evidence of the threat is not subtle or ambiguous. It sits right in front of us in plain sight.
Suppose that, within the space of one month, terrorists using shoulder-fired missiles shoot down two 747s and two regional passenger aircraft. Examination of such a scenario leads inexorably to six conclusions:
One successful large-airliner shoot-down would be viewed as a freakish tragedy. But two successful attacks spread over a few days or weeks would be viewed as a pattern, an indicator of things to come. Statistically, one might argue that air travel remained safer than automobile travel regardless of whether there had been zero, one, two, or five successful attacks. But the psychological impact of serial shoot-downs would likely be extreme.
Immediately, the flying public would conclude that commercial aviation is unsafe.
Insurers would sharply increase their projections of the risk of commercial flight. Hull and liability insurance could become unavailable or prohibitively expensive. Passenger ticket sales could fall catastrophically because of fear and a sharp increase in ticket prices. Consider, for example, a world in which the cheapest coach seats are priced higher than today's unrestricted first-class seats.
The very survival of all air carriers, aircraft manufacturers, and their supporting industries would be endangered, as would those industries whose operations depend on air transportation. Civilization's ability to move people and goods rapidly over long distances could be lost.
Direct casualties from downing a handful of passenger jets would be in the hundreds, well under those of 9-11. But the socioeconomic cost would be far greater, deep in the hundreds of billions of dollars at least, depriving the world of rapid transportation, and probably triggering a worldwide recession or depression from which recovery cannot be predicted.
It is true that although the total number of civilians killed by terrorist use of shoulder-fired missiles against smaller aircraft to date approximates the passenger load of a large airliner, the socioeconomic impact of these attacks has been minimal. Similarly, many more people died in previous shipwrecks than in the sinking of the Titanic, but it was the latter that stimulated such obvious steps as requiring liners to carry enough lifeboats to hold all the passengers. The difference is psychological. Small numbers of large airliners carry a psychological and political salience that larger numbers of smaller aircraft do not.
TERRORIST INTENT TO ATTACK AIRLINERS
Recent history finds ample evidence of accelerating terrorist attempts to attack passenger aircraft with shoulder-fired missiles. The most notable incidents include --
1994-A Falcon-50 executive jet carrying the Presidents of Rwanda and Burundi is shot down, igniting massive ethnic violence.
1997-Rebels shoot down a Yugoslav government transport, killing five.
1998-A Congo Airlines 727 airliner is shot down by rebels, killing all 40 aboard
1999-Rebels in Angola shoot down a United Nations C-130 transport, killing 14.
2001-Rebels in Angola hit, but fail to destroy, a United Nations 727 cargo aircraft.
2002-An expended surface-to-air missile launch tube is found near Prince Sultan Air Base in Saudi Arabia.
2002-Two missiles are fired at an Israeli chartered 757 with 271 on board as it takes off from Mombasa, Kenya. The missiles are seen by the pilot as they fly by and miss.
2002-A young man openly carrying a fully functional late-model Russian shoulder-fired anti-aircraft missile is arrested on a street in St. Petersburg. He had found the missile on a shooting range and was taking it home to show his friends.
2003-At least two missiles are fired at US Air Force aircraft landing at Baghdad airport, but miss.
2003-Three arms dealers are arrested in a sting in New Jersey for attempting to sell the first of 200 Russian SA-18 missiles to an apparent Sudanese terrorist explicitly for use against American airliners. Fortunately apparent supplier of the missile was a Russian counter-terrorist agent, the missile was intentionally inoperable, the apparent Sudanese terrorist buyer was an FBI agent, and the arms dealers are now in custody and awaiting trial.
An accurate count of shoulder-fired anti-aircraft weapons is impossible, but worldwide they appear to number in the mid to high hundreds of thousands with most, of course, in the hands of national militiaries. The number of terrorist organizations known to possess them appears to number in the low teens.
Fire and forget missiles
Shoulder-fired anti-aircraft weapons typically use fire-and-forget infra-red guidance, homing at supersonic speed on the heat signature of the target aircraft. All are capable of being carried and fired by one man, although operation usually consists of a two-man crew with two missiles. Typical system weight is about 35 pounds. All are about the size of a trombone. All can be readily concealed and fired with preparation time of a few seconds. Generally they are "wooden rounds," requiring no maintenance.
Because of their lightweight warheads, a direct hit is required to do significant damage, and fusing is by contact with the target. Probability of kill per hit should be assumed to be high, but is a subject of considerable debate. C-17 advocates, for example, claim that a direct hit on one of the four C-17 engines would cause that engine to break away, leaving the aircraft crippled but flyable. This should be taken with a grain of salt; the location and precise effect of a missile hit is unpredictable.
Fire and forget missiles of concern here include, in order of increasing capability:
SA-7a Strela 2
(SA-XX is the NATO designator for surface-to-air missiles of the former Soviet Union. Stingers are US missiles.)
The most widely-deployed of these missiles is the SA-7b, which was probably the weapon used in all the attacks listed above. Using Vietnam-era technology, its nominal range is about 3 miles and nominal altitude about 10,000 feet, but its effective footprint is somewhat less than that. Its speed is about Mach 1.6, its maneuverability about 6G, and its maximum flight duration before self-destruct is about 15 seconds. Its seeker technology generally limits it to operating in tail-chase mode.
Moving down the list, the missiles progressively increase in range, altitude, speed, and maneuverability. A step increase in effectiveness begins with the Stinger Basic, which has a superior seeker capable of detecting and tracking aircraft engine heat from any aspect, thus radically increasing its attack opportunities.
Another step increase is found beginning with SA-18, which uses a two-color seeker. This enables the missile to distinguish and respond to the spectral differences between the emissions of an engine and those of a conventional pyrotechnic flare.
Several thousand Stinger Basics were given to the mujaheddin to help resist the Soviet occupation of Afghanistan. It appears that two or three hundred of these Stingers remain unused and are in the hands of Al Qaida remnants, or of similar sub-national entities that bear no love for Western civilization. These missiles are old, more than twice their rated storage life of eleven years. While their reliability is uncertain, they must be considered a highly significant threat to commercial aviation-as are the several thousand SA-18s and the much larger number of their earlier brothers dispersed around the world.
Laser-guided shoulder-fired anti-tank missiles
Some commentators have suggested that laser-guided missiles such as the British Blowpipe are particularly dangerous because they are relatively immune to countermeasures. But they require the operator to hold a laser spot on the target throughout the flight of the missile. This is a highly demanding task and would probably deter or defeat terrorist use of laser-guided anti-aircraft missiles.
Anti-tank missiles used against aircraft
Because of the use of RPG light anti-tank missiles against hovering helicopters in Somalia, dramatized in the motion picture "Blackhawk Down", there is some public concern about possible RPG attack against airliners. While freak events can happen, basically this concern is misplaced. The RPG is an unguided, rifle-sighted missile with range limited to a few hundred meters. Its short range denies it a useful tail-chase or head-on opportunity, and its unguided nature renders a shot from the side almost certain to miss.
On the other hand, although this has not been demonstrated, a very smart anti-tank missile such as the US Javelin might be effective in a head-on shot.
WHAT CAN BE DONE
There is no silver bullet. No single countermeasure can shield all airliners from all shoulder-fired missiles under all conditions. But there are a variety of countermeasures that, in combination, can provide significant risk reduction.
It is now possible to retain use control of shoulder-fired missiles even if physical possession is lost. Missiles can be designed with a chip-level feature that requires enabling by an electronic password before the missile will activate.
This does not mean that a soldier with a hostile aircraft or tank bearing down on him will have to look up a password in a code book and type it in before he can defend himself. On the contrary, the password can be entered by radio signal or various other automated means, and the missile can remain enabled for whatever duration the command chooses, be it two minutes or two years. But after the password expires, the missile will never again enable unless the password is re-entered.
This solution would not be a disabler such as a trigger lock. A disabler could be removed, leaving the missile operable. Rather, it would be a controllable enabler, built in as part of the missile's highest-tech circuitry. Removal of the enabler circuitry could only be done by removing key components without which the missile could not operate.
Similar features, called Permissive Action Links, have been used in more elaborate form in US nuclear weapons for many decades. A low-cost consumer version has long been used in some automobile radios. If the radio is removed from the car, it goes dead and will never again operate unless it receives a code held by the manufacturer. So these radios have no value if stolen.
Since controllable enabling would be built in at the chip level, it would add no weight and no measurable production cost for new missiles. There would be design cost but this would be small.
Irreversible retrofit of existing missiles would be technically challenging and much more expensive. The key problem would be to prevent non-controlled components from being re-installed as retrofits, replacing the controllable enabler. But tamper-proofing and other safeguards can probably render this beyond terrorists' capabilities.
That being said, of course controllable enabling can't be applied to missiles already in hostile hands.
WHAT IS BEING DONE
For a decade and a half, some agencies of Government have pressed hard for controllable enabling of shoulder-fired missiles. Regrettably, the US Army was not among them.
Controllable enabling was mandated by Congress in the 1988 Defense Appropriation Bill. The Appropriations Committee report specifies that "$4 million....only may be used to develop without delay a device to neutralize any diverted Stinger missiles. The Committee is concerned that the Army has not assigned sufficient priority to this effort in the past."
The following year, the Appropriations Committee made a similar recommendation with respect to the Javelin anti-tank missile, reflecting concern that it could present a severe threat against any ground target including a Presidential limousine. And in 1995, the Arms Control and Disarmament Agency sought to interest the Army in building controllable enabling devices into all of its shoulder-fired missiles.
In all cases the Army's response was, in essence, "We could do this but we won't. It's not our job."
While the Army's recalcitrance was in a sense irresponsible, in another sense it was understandable. Both Stinger and Javelin were pushing the limits of technology. Their designers' task was to give American soldiers missiles to do what no soldiers had ever done before. The last thing the designers wanted was an additional requirement not part of their core mission.
9-11 was a wake-up call in this, as in many other respects. The Department of Defense now understands the need to safeguard shoulder-fired missiles. But no program for controllable enabling has yet emerged.
Airport monitoring and patrolling
Intense surveillance of the airport area, including the use of helicopter patrols, requires no new technology and has the advantage of being able to be ramped up relatively quickly. For airports surrounded by water or barren terrain, this can be quite effective, particularly against short-range missiles such as the SA-7. But Stinger and SA-18 footprints can be larger than 150 square miles and typically include large highly built-up areas that cannot be policed.
Active defense of commercial aircraft
Since the infra-red guidance systems on shoulder-fired missiles are passive, emitting no radiation of their own, detecting and tracking an incoming missile is inherently difficult.
The traditional military defense against heat-seeking missiles has been the use of pyrotechnic flares, released preemptively when the aircraft is in a threat area. A flare's strong point-source of light causes the missile to go for the flares rather than the airplane. But the penalties of dropping incendiary flares on populated areas near airports are prohibitive. Two active defense systems, using sharply differing technologies, are now in wide use.
The Northrop Grumman Large-Aircraft Infrared Countermeasure (LAIRCM) detects and tracks the missile by a staring ultra-violet device which has full-circle coverage in the downward hemisphere. It then attacks the missile's seeker with an infrared laser, modulated to distort the flight path of the missile. It is internally installed in about 150 US and UK military aircraft of 20 different types including the C-17, MC-130 and MH-53. According to press reports, is it also in Air Force One and Air Force Two. For commercial airliners it would be retrofitted in a small pod added to the rear lower fuselage.
The Israeli Aircraft Industries Flight Guard uses a pulse Doppler radar to detect and track an incoming missile by its motion. The system then automatically dispenses "safe flares" which are charges of hot gas rather than burning solids, and are claimed to leave no residue falling to the ground. Six antennas give all-aspect coverage. The system is installed on about 150 aircraft, and is claimed to have successfully defended against an SA-18 attack. This implies that, unlike conventional pyrotechnic flares, the gas flares simulate jet engines well enough to deceive a two-color seeker. The system has been certificated for use in airliners by the Israeli government, but in the US the explosive flare canisters appear to be creating a safety concern.
Modifications can reduce the infra-red signature of commercial aircraft. For example, non-reflective paint could help significantly. Flat paint adds aerodynamic drag and looks dirty. But according to a recent Congressional Research Service report, the airlines' primary aversion to flat paint is that it would openly acknowledge the threat and thereby upset passengers. This attitude is inexcusable. Failing to take countermeasures, in a futile attempt to pretend the threat is not there, will needlessly increase the risk to passengers.
Abandoning noise-abatement requirements and using maximum-climb departures would significantly reduce the footprint of shoulder-fired missiles, at the expense of greatly increased noise in the area close under the takeoff path. In some cases, presently pleasant neighborhoods could become unsuited for residential use.
Similarly, missile footprints could be further reduced by altering the landing approach. Military transports flying into known threat areas such as that now around Baghdad airport maintain altitude above missile reach until they are close to the airport, and then execute a sharp spiral descent. Adapting this for commercial airliners would create safety issues, would require upgrading the landing systems at most airports, and would reduce the number of landings that could be accommodated per unit time. A more moderate solution would be simply to stay higher longer and then descend more sharply, to the extent that this can be done without creating excessive airspeed.
One commentator has argued that "Successful evasion is a low-cost, near-term solution to the threat. A trained pilot can be very effective in evading missiles." This is nonsense and should not be pursued. An airline pilot has zero vision to his rear hemisphere; the first he would know of a missile attack would be when he felt the impact. If he were to be warned by an external source, it would still not be credible to attempt to outmaneuver a missile. Even the SA-7 is capable of 6G maneuvers, while an airliner on takeoff would be in severe distress at 3Gs. Transient maneuverability (the ability to quickly roll, pitch, or add Gs) of airliners is weak. An airliner is not intended to be an F-16, which can flick into a vertical-bank hard turn in the blink of an eye. And even an F-16 would not win many maneuverability contests against a Stinger.
The traditional method of controlling such weapons is to restrict sales and to require end-use agreements. We only transfer them to our friends, we ask that they be rigorously guarded, etc. Certainly this is essential; otherwise Al Qaida could simply buy Stinger RMPs over the counter. But export controls are a partial solution, porous even under the best of circumstances. Weapons are not always perfectly guarded in peacetime. In wartime they can be dropped on the battlefield, picked up by the other side, and used or sold without restriction.
Many governments realize that they have more shoulder-fired weapons than they need. They are willing to destroy them, but are concerned about cost and other issues. The State Department is currently working with these governments to develop plans under which the United States will give technical and financial help with destroying the missiles.
RECOMMENDATIONS FOR THE US GOVERNMENT
1. Recognize the urgency of the problem and respond with Manhattan-project priority
We have heard many government statements such as that by Brian Roehrkasse of the Department of Homeland Security that "These weapons pose a threat, but there is no specific credible evidence that they are in the hands of terrorists in the United States or that they plan to use them to shoot down airliners."
For US policy-making purposes, whether these weapons are now in the United States doesn't matter. Nor does it matter if at this moment terrorists do not have plans to shoot down airliners. Terrorists have the weapons, and can bring them into the United States within days. The terrorist motivation exists, and plans can change in minutes. But most of the solutions will take months or years to implement. If we wait until the threat stares us in the face and then reach for solutions, the most effective ones won't be there. We will have let our adversaries operate inside our decision loop, very far inside. Civilization will likely lose, and lose badly.
In absolute terms, an urgent drive for solutions costing billions or tens of billions of dollars will not be cheap. But relative to the cost of failure, it will be very cheap.
2. Recognize the breadth of the shoulder-fired missile problem.
It is not confined to anti-aircraft missiles. It includes advanced anti-tank missiles. Thus, the common term MANPADS (Man-Portable Air Defense Systems) is too narrow.
3. Rapidly develop and begin production of controllable enabling devices for Stinger and Javelin.
4. Immediately stop work on all final assembly and upgrade of shoulder-fired missiles, and on all sub-assemblies (usually the seekers) on which controllable enabling should be installed.
Resume production when controllable enablers can be included. This will be disruptive and costly. But that very fact will send a persuasive message to other governments that we are very serious about preventing terrorist use of shoulder-fired missiles.
5. Immediately negotiate with other producer nations about installing controllable enablers in their shoulder-fired missiles.
Consider sharing the technology wherever possible. Controlling shoulder-fired missiles is in the self-evident interest of every non-terrorist government.
6. Significantly augment airport patrols.
Sen. Boxer recently described walking up on the roof of an airport building and standing unobserved within easy SA-7 range of departing airliners. This is an experiment most of us could probably repeat, in many variations and with little difficulty. Augmented patrols are one step that doesn't take new technology and can be done rapidly.
7. Establish a government program of aircraft hull and liability insurance.
Rates should be higher than present commercial rates, so the program would not be used unless and until there were a successful attack. But it would be immediately available if commercial rates were to zoom, or coverage to vanish, after an attack. The purpose of the program would not be per se to compensate victims of future attacks. It would be to enable commercial air operations to continue and thereby avoid economic disaster. More fundamentally, it would send a message to terrorists that shooting down airliners would not cause economic collapse. The very act of sending this message could remove much of the motivation for an attack.
Establishment of such a program will require many months as the Administration develops its plan, the House and Senate each modify, debate, and pass their separate versions, and the differences are resolved in conference. Therefore it needs to be done preemptively, in the near term, so it can be on the shelf ready for immediate use if the occasion arises.
8. Fund the accelerated production and installation of both active and passive airliner defense equipment.
A bill by Sen. Barbara Boxer (D-CA) and Rep. Steve Israel (D-NY) provides for government funding to install active defenses in the 6800 existing jet airliners on scheduled service. This should be done, beginning with the largest widebodies. Large freight and charter aircraft should also be included. The Boxer-Israel bill also provides for installation to begin in December of this year. That is too quick; the goal is good but the engineering can't be done that soon. The Administration's program, in contrast, would probably lead to first deployment in 2006. That is unnecessarily slow, in light of the fact that two systems are already operating successfully in military aircraft. This schedule should be substantially accelerated. Passive measures including nonreflective paint can be installed within months at low cost.
9. Evaluate the cost and benefit of more rapid climb and descent for airliners in light of the shoulder-fired missile threat.
10. Vigorously pursue negotiations, many of which are now ongoing, with foreign governments on controlling proliferation of shoulder-fired weapons and on destroying surplus missiles.
11. Sting, sting, and sting again.
The recent spectacular success of the US and Russian governments in catching an arms dealer hoping to sell SA-18s for fun and profit should be the first of many such operations. Critics have accused it of merely proving that if somebody wants to sell missiles, he can always find a buyer. This misses the point. On the contrary, it proves that if somebody tries to buy missiles illegally, he can expect to spend the rest of his life in prison. If this is demonstrated repeatedly, the number and enthusiasm of buyers can be significantly impacted.
12. This above all things: In making any decision on shoulder-fired missile policy, fully contemplate the price of failure.
Author's note: Robert Sherman, a principal in the consulting firm of Carr Sherman Minjack, was formerly the Director of the Advanced Projects Office at the Arms Control and Disarmament Agency and Director of the Strategic Security Project at the Federation of American Scientists.