Syria Support Movement solidarity with the Syrian people
Oct 3, 2013, Asia Times
US President Barack Obama’s reversal on the bombing of Syria took the world by surprise. For a long time, he was talking about the use of chemical weapons by Bashar Al-Assad’s regime being “a red line”. There was a feeling that Obama’s talk about chemical weapons use in Syria was like a proverbial “Chekhov’s gun” – in a well-written play, if a gun is seen in the first act hanging from a wall, in the last act it must shoot.
Obama certainly knew for a long time that most Americans and were against involvement in Syria. He himself said that he was not obliged to ask the Congress permission for a remote-control war. Then suddenly the reversal. It certainly looks like something happened that he did not expect.
Nobody in the mainstream media had analyzed technical aspects of the attack, and nobody to my knowledge doubted the ability of America’s armed forces to execute it. Yet this author’s analysis, based mainly on data from open sources and technical common sense, shows that the reason for this reversal can very likely be found in limitations in military capability to execute a “clean” overwhelming strike on Syria.
If this is true, it would be understandable that Pentagon generals if did not want to bring the bad news to Obama, in the hope that something would happen that would get them out of the predicament. Only as the moment of truth was approaching, perhaps, was Obama notified that his strike plan could not be executed for technical reasons.
It was announced that the American attack on Syria would be conducted with an opening salvo of several hundred Tomahawk missiles launched from US Navy ships deployed in the Mediterranean sea. This is a tactic usually used by the US against an adversary with a credible air defense system. Only after enemy air defenses are degraded to the point that losses of manned aircraft are unlikely does aerial bombing start, followed if necessary by ground troops or local US allies. This approach allowed the US to conduct its recent campaigns in Iraq and Libya with astonishingly low losses.
The Tomahawk is a weapon that is not suitable for area bombing due its high cost. Its use makes sense only for precise destruction of high-value targets. At an announced US$1.5 million per shot, even the US cannot afford to use more than several hundreds of these weapons. In contrast, the cost of an aviation bomb, including delivery, is probably in the tens of thousands of dollars.
The claimed accuracy of Tomahawk is to 10 meters. It is further claimed that 90% of engaged targets are destroyed. How is this precision achieved?
The Tomahawk has multiple guidance systems – GPS (Global Positioning System), INS (Inertial Navigation System), TERCOM (Terrain Contour Matching), DSMAC (Digital Scene Matching Area Correlation). TERCOM uses radar altimeter data to compare with a stored map of the terrain. It is clear that it cannot work over flat terrain or over water, and even over a more feature-rich terrain it probably has a large probability of loosing orientation.
DSMAC is based on comparing a stored image of the target area with the image produced by the on-board optical camera. DSMAC may work to identify an isolated building in a desert, but this author doubts it works reliably in complex scenery, especially in an urban environment.
Both of the above methods require data to be available and loaded into the missile computer in advance, while GPS-identified targets can be programed in flight. It is not clear if the US Army can produce data for DSMAC out of satellite data or if aerial reconnaissance is required for every target.
Modern INS for civilian airplanes has a nominal position error of two nautical miles an hour. There is no reason to believe that military systems are at present more accurate. This means that in the absence of a GPS signal for a substantial period of time, necessary guidance precision is lost. A military airspace journal quotes an official saying that loss of precision occurs after 30 seconds of GPS signal loss. [1]
One can conclude that the precision, flexibility, and ease of re-targeting of Tomahawk missiles are based on GPS, and that all auxiliary guidance systems do not work universally and may not be suitable at all under certain circumstances, depending on such aspects as the type of terrain between the launcher and the target.
This problem is acknowledged in specialized publications. Military and Aerospace Electronics [1] quotes unnamed officials from the US Defense Advanced Research Projects Agency (DARPA) as saying that “military reliance on GPS signals for precision positioning, navigation, and timing (PNT) information is crucial for a wide range of military weapons”.
In a book published by the US National Defense University [2] adds that “the military establishment has already identified and acknowledged the susceptibility of their newest generation GPS-assisted weapons to jamming. Without the availability of precision munitions and the conditions necessary for their successful employment, the requirement for numbers of sorties and the risk associated with every strike increases exponentially.”
That last statement was made in 2002, but quite recently in Military and Aerospace Electronics [3] an Air Force official, Dan Faulkner, admitted that the problem is very far from being solved. According to Faulkner, the US is developing guidance systems that can operate without GPS, but these systems that are 20 to 30 years away from becoming operational.
On April 16, 2012, DARPA announced that it is soliciting research on Chip-Scale Combinatorial Atomic Navigator (C-SCAN). To quote, “the program seeks to address challenges associated with the long-term drift, dynamic range, and start-up time of chip-scale components for positioning, targeting, navigation, and guidance tasks.” [4]
This is supposed to be an advanced INS system that would allow precise weapon guidance without necessity in any external signal. This system, however, is not going to be available soon. In the meantime, US adversaries are undoubtedly putting much effort into creating systems capable of neutralizing “smart” weapons.
In 2009 at the Moscow International Aviation and Space Salon, a Russian company exhibited GPS jammers for military application. This author spoke with the chief engineer of the company, who claimed that its equipment was employed in Iraq in 2003 and initially caused Tomahawk missiles to fly wildly off course as far as Turkey. According to him, Iraq’s mistake was to buy only a small number of jamming devices, which the Americans were able to destroy before resuming use of GPS-guided missiles.
GPS jamming devices should not be expensive in mass production. It should be possible to buy hundreds or thousands of them for the price of one Tomahawk missile.
There are two currently available systems to increase resistance of GPS devices to jamming. One seeks to achieve a tight coupling between GPS and INS using advanced software. [5] This method can help when GPS jamming is intermittent, but not when the missile flies through a continuous zone where GPS is completely suppressed. The second method is using a directional antenna to block reception in the direction of one or several jamming sources. One such system [6] is offered by Canadian company NovAtel. However, it is doubtful that such a system, even if it is already installed on Tomahawks, would work against multiple sources and strong jamming signals.
We can suppose that Syria learned from Iraqi and Libyan experience and obtained a sufficient amount of GPS jamming devices from Russia. Hundreds or thousands of these devices can easily cover a large area around Damascus and other important areas, so that cruise missiles would fly off course by hundreds of kilometers. The GPS jamming zone can start over water, where TERCOM and DSMAC guidance surely do not work. With the use of small boats, a jamming zone can be extended hundreds kilometers from the shore.
An additional restriction is that the presence of advanced anti-ship missiles supplied by Russia does not allow American ships to come close to Syrian shores for the attack, so missiles have to fly long distances over water, likely without a GPS signal, and this will lead to difficulties in resuming TERCOM navigation when overland.
In these conditions, Pentagon generals could not guarantee the clean and impressive victory Obama had expected. Of course, nobody can predict the results of Tomahawk strikes with complete certainty, but in all likelihood it would be inconclusive at best. What could the poor generals do next? Send bombers into mostly intact anti-aircraft defenses and risk substantial aircraft losses and further embarrassment?
A far more reliable solution would be to make a virtue out of necessity, and ask a reluctant Congress to approve the strike, and after being rebuffed announce another great victory for American democracy.
Notes: 1. Military & Aerospace Electronics, DARPA seeks to wean smart weapons off GPS with hybrid inertial navigation system-on-a-chip, By John Keller, April 18, 2012.
2. Globalization and Maritime Power, edited by Sam J Tangredi, National Defense University, Chapter 18, Globalization and Naval Aviation, by J Kevin Mattonen, 2002.
3. Military & Aerospace Electronics, Electronic warfare: the cat-and-mouse game continues, by J R Wilson, September 9, 2013.
4. Chip-Scale Combinatorial Atomic Navigator (C-SCAN), Solicitation Number: DARPA-BAA-12-44, April 16, 2012.
5. Aviation International News, GNSS Advances, Despite Setbacks, by John Sheridan, September 2013.
6. GAJT, GPS Anti-Jam Technology, NovAtel Inc., Calgary, Alberta, Canada.
