What Future for GPS?
Ecce Homo! Loquitur...
Thread Starter
What Future for GPS?
AWST (Ares): Back Away from GPS: AF Chief
In the face of threats from jamming and attacks on satellites the United States must lessen its dependence on the Global Positioning System and develop alternatives to GPS, the top Air Force general said today.
Gen. Norton Schwartz, Air Force Chief of Staff, told a conference organized by Tuft University’s Institute for Foreign Policy Analysis that GPS signals are particularly vulnerable in time of war since enemies know of the reliance U.S. forces place on its highly accurate signal. Everyone has read about the amazing accuracy of smart bombs and cruise missiles but few remember that those weapons depend on receiving a signal from a constellation of satellites orbiting the earth.
Schwartz’s call is driven by serious threats to GPS, according to officials familiar with the issue who would not discuss current threats in detail but confirmed that GPS has been jammed or interfered with recently.
The fact that the U.S., which invented GPS and most of what depends on it (ATMs, gas pumps, trucking companies and lost spouses), would consider stepping away from the system marks a cultural and technological milestone
Among the tools that could be used to lessen the dependence of troops on GPS are highly accurate digital maps which can be distributed electronically or even rely on that quaint old technology known as printing. In more developed environments cell phone tower networks can be used as does Apple’s iPhone. Of course, the US would have to control the cell phone network for that to work.
Schwartz’s comments come as the Space Posture Review, scheduled for release with the QDR but now delayed for as long as a year, has tentatively recommended that the U.S. scrap building five more GPS satellites and engage European allies on sharing their proposed Galileo global navigation satellite system.
In the face of threats from jamming and attacks on satellites the United States must lessen its dependence on the Global Positioning System and develop alternatives to GPS, the top Air Force general said today.
Gen. Norton Schwartz, Air Force Chief of Staff, told a conference organized by Tuft University’s Institute for Foreign Policy Analysis that GPS signals are particularly vulnerable in time of war since enemies know of the reliance U.S. forces place on its highly accurate signal. Everyone has read about the amazing accuracy of smart bombs and cruise missiles but few remember that those weapons depend on receiving a signal from a constellation of satellites orbiting the earth.
Schwartz’s call is driven by serious threats to GPS, according to officials familiar with the issue who would not discuss current threats in detail but confirmed that GPS has been jammed or interfered with recently.
The fact that the U.S., which invented GPS and most of what depends on it (ATMs, gas pumps, trucking companies and lost spouses), would consider stepping away from the system marks a cultural and technological milestone
Among the tools that could be used to lessen the dependence of troops on GPS are highly accurate digital maps which can be distributed electronically or even rely on that quaint old technology known as printing. In more developed environments cell phone tower networks can be used as does Apple’s iPhone. Of course, the US would have to control the cell phone network for that to work.
Schwartz’s comments come as the Space Posture Review, scheduled for release with the QDR but now delayed for as long as a year, has tentatively recommended that the U.S. scrap building five more GPS satellites and engage European allies on sharing their proposed Galileo global navigation satellite system.
Join Date: Jan 2008
Location: Glasgow
Age: 61
Posts: 909
Likes: 0
Received 0 Likes
on
0 Posts
Future of GPS
I am providing a very brief response, and one that does not answer fully all points (lack of time on my behalf).
GPS & Glonass currently make up GNSS (Global Navigation Satellite System ) and Galileo will join this mix. All three together shall provide a reasonably robust mix.
Areas of weakness are physical attacks to ground based and space based components along with jamming of signals. Another way would be the introduction of spurious data signals.
Currently the GPS (US system) utilises L1, L2, L3, P1 and a number of other frequencies which are or may come on line as required. GLONASS and Galileo use other frequencies. You have multiple frequencies for each system and multiple point sources as well. All of the systems depend upon a ground component to give increased accuracy. If any one tries to Jam GPS systems it is very, very difficult. This is due to multiple redundcies of frequencies, satelittes, software, etc.
As for physically attacking satellites that is currently extremely difficult and extremely costly. In the future when laser technology may be more effective at a lower cost satellites can be protected. Costly, but it is possible. Satellite missile attacks are more difficult to protect from.
There is no techology currenlty available which provides the seeming simplicity and accuracy of GPS systems (used here as a generic term for satellite based positioning systems).
The wide spread usage within civilian systems (from mobile telephones to surveying and from vehicle trackers, to oil exploration) tends to provide some system protection in that it is unlikely that systems will be withdrawn from use.
Hval
Edited for an incorrectly placed full stop
GPS & Glonass currently make up GNSS (Global Navigation Satellite System ) and Galileo will join this mix. All three together shall provide a reasonably robust mix.
Areas of weakness are physical attacks to ground based and space based components along with jamming of signals. Another way would be the introduction of spurious data signals.
Currently the GPS (US system) utilises L1, L2, L3, P1 and a number of other frequencies which are or may come on line as required. GLONASS and Galileo use other frequencies. You have multiple frequencies for each system and multiple point sources as well. All of the systems depend upon a ground component to give increased accuracy. If any one tries to Jam GPS systems it is very, very difficult. This is due to multiple redundcies of frequencies, satelittes, software, etc.
As for physically attacking satellites that is currently extremely difficult and extremely costly. In the future when laser technology may be more effective at a lower cost satellites can be protected. Costly, but it is possible. Satellite missile attacks are more difficult to protect from.
There is no techology currenlty available which provides the seeming simplicity and accuracy of GPS systems (used here as a generic term for satellite based positioning systems).
The wide spread usage within civilian systems (from mobile telephones to surveying and from vehicle trackers, to oil exploration) tends to provide some system protection in that it is unlikely that systems will be withdrawn from use.
Hval
Edited for an incorrectly placed full stop
I don't own this space under my name. I should have leased it while I still could
If any one tries to Jam GPS systems it is very, very difficult. This is due to multiple redundcies of frequencies, satelittes, software, etc.
To achieve the aim of GPS degradation it is not necessary that the signal be jammed and disrupted. It is far more effective if the jamming is subtle and the GPS receiver is seduced from its true position.
Against PGM it is necessary only to inject a small error in the region of 400 metres - quite sufficient to avoid the weapons effects and sufficiently small as to be attributable to some guidance control malfunction. A bonus might be to achieve a blue on blue.
Against a ground unit in featureless terrain an induced error of only 100 metres would be suficiently disruptive.
Some years ago there were instructions issued that commercial OTS GPS was not to be used in combat areas. It was interesting therefore to see the RN using the same Garmin GPS that I have to prove that the IPod 15 were in international waters.
Total reliance on a single source of position information is foolish.
I suspect that this is all political posturing. There's no way that the ooorah-jingoistic spams would ever contemplate a proposal to
unless it was to steal technology or gain some other high ground. No doubt they don't like the fact that someone other than Uncle Spam has been contracted to put the first operational Galileo vehicles in orbit either.
If you compare the performance of an early Garmin with the performance of a current Garmin in your car, you will note that, even though signal reception might be identical, later models are much cleverer. They 'know' that, if the 'present position' as received from satellites suddenly buggers off over the nearest hedge, the system's intelligence thinks "Well, I'm still doing 50 mph, so I'm probably still on the mapping's roads - and that's what I'll assume until the GPS gets its $hit together again". Some car systems use a LINS and/or wheel velocity sensors to confirm acceleration rates, but even with a basic standalone system, I've seen significant positional CEPs displayed which still haven't upset the car-on-road position.... It amuses me the way a Garmin 'tracks' your progress through a tunnel much as 'last known velocity' was used in certain ECCM modes of the Phantom's MCS.
Much as velocity rate limiters can prevent (probably classified) AAM decoying methods, it doesn't take much synergy to defeat seduction of GPS present position using another system - even basic acceleration rate gates.
Sorry, General, you'll have to fund your own GPS upgrade.
....engage European allies on sharing their proposed Galileo global navigation satellite system.
If you compare the performance of an early Garmin with the performance of a current Garmin in your car, you will note that, even though signal reception might be identical, later models are much cleverer. They 'know' that, if the 'present position' as received from satellites suddenly buggers off over the nearest hedge, the system's intelligence thinks "Well, I'm still doing 50 mph, so I'm probably still on the mapping's roads - and that's what I'll assume until the GPS gets its $hit together again". Some car systems use a LINS and/or wheel velocity sensors to confirm acceleration rates, but even with a basic standalone system, I've seen significant positional CEPs displayed which still haven't upset the car-on-road position.... It amuses me the way a Garmin 'tracks' your progress through a tunnel much as 'last known velocity' was used in certain ECCM modes of the Phantom's MCS.
Much as velocity rate limiters can prevent (probably classified) AAM decoying methods, it doesn't take much synergy to defeat seduction of GPS present position using another system - even basic acceleration rate gates.
Sorry, General, you'll have to fund your own GPS upgrade.
Join Date: Jan 2008
Location: Glasgow
Age: 61
Posts: 909
Likes: 0
Received 0 Likes
on
0 Posts
Pontius Navigator
Agreed. Which is why I said don't rely on one data source, rely on three - GPS, GLONASS & Galileo. I apologise for the next bit.
Not only that but you are able to do some extremely clever stuff with some nav kit. We call it Coctkail. If spurious data is introduced then there will be a "Gate Out" or a "Rate Out" or both. When this happens the spurious data source is detected. Software then kicks out the spurious data and any suspect Nav system. So, I might use one gps antenna, one glonass antenna and one galileo antenna. However I would use two processors for each antenna. For the GPS system you can make use of different frequencies and there are a number of new chips being introduced for this. As an addition you could even add another type of navigational system just to give you a different source for your cocktail. These sources could include INS - which I generally wouldn't touch with a barge pole as they are effected by gravity and even gravity surveys mapping mountains, gravity sources, coastal grav surveys etc don't produce perfect solutions. You could also make use of mobile phone masts, chayka, argo etc.
With modern day technology it is surprising how small a space can be taken up with a mixture of systems.
I could go on and get even more technical including the mathematics behind the systems and processing, but I won't.
Hval
Total reliance on a single source of position information is foolish.
Not only that but you are able to do some extremely clever stuff with some nav kit. We call it Coctkail. If spurious data is introduced then there will be a "Gate Out" or a "Rate Out" or both. When this happens the spurious data source is detected. Software then kicks out the spurious data and any suspect Nav system. So, I might use one gps antenna, one glonass antenna and one galileo antenna. However I would use two processors for each antenna. For the GPS system you can make use of different frequencies and there are a number of new chips being introduced for this. As an addition you could even add another type of navigational system just to give you a different source for your cocktail. These sources could include INS - which I generally wouldn't touch with a barge pole as they are effected by gravity and even gravity surveys mapping mountains, gravity sources, coastal grav surveys etc don't produce perfect solutions. You could also make use of mobile phone masts, chayka, argo etc.
With modern day technology it is surprising how small a space can be taken up with a mixture of systems.
I could go on and get even more technical including the mathematics behind the systems and processing, but I won't.
Hval
Join Date: Jan 2008
Location: Glasgow
Age: 61
Posts: 909
Likes: 0
Received 0 Likes
on
0 Posts
Beagle
I do know that the USA is not happy with other nations having their own technology. This has been stated by them openly. They really were grumpy about Europe going for Galileo and gave lots of grief. Means they can't use the P code.
Hval
unless it was to steal technology or gain some other high ground.
Hval
Join Date: Jun 2001
Location: Island of Aphrodite
Age: 75
Posts: 530
Likes: 0
Received 0 Likes
on
0 Posts
[QUOTE]"In the face of threats from jamming and attacks on satellites the United States must lessen its dependence on the Global Positioning System and develop alternatives to GPS, the top Air Force general said today.
Gen. Norton Schwartz, Air Force Chief of Staff"[QUOTE]
Ironic that he says this in the same week that Loran C is switched off by the US. (Some chains not US controlled still on)
Gen. Norton Schwartz, Air Force Chief of Staff"[QUOTE]
Ironic that he says this in the same week that Loran C is switched off by the US. (Some chains not US controlled still on)
My opinion of various GPS vulnerabilities at the unclass level:
1. Shoot Down
A few numbers should suffice:
GPS orbital altitude: 20,200km (in Medium Earth Orbit, along with GLONASS and Galileo)
Altitude of weather satellite shot down by China: 850km
The technology demonstrated by China only threatens satellites in Low Earth Orbit (up to 2000km, e.g. reconnaissance satellites). Furthermore, GPS has significant redundancy, with (currently) 30 satellites in orbit, so would withstand a degree of attrition.
2. Jamming
As already stated above, GPS is now operating on a greater range of frequencies. The bandwidth of the military frequencies makes jamming a lot harder. Not willing to say anything else!
3. Spoofing (vs airborne platforms only)
Every course I've been on that covers GPS gets round to the subject of spoofing. I don't claim to be an expert on the subject (and a little bit of knowledge can be a dangerous thing
) but you don't need to be a techno-whiz to understand the following:
Controlled Radiation Pattern Antennae (CRPA) provide a further robust antidote to both jamming and spoofing. Google can provide more details for you and then I don't have to tread a fine line of classification.
Anyway, in summary, I don't feel like I need to dust down the old sextant or Dalton computer just yet. Perhaps the General's statement is just designed to keep would-be jammers and spoofers spending money on developing ineffective countermeasures...
1. Shoot Down
A few numbers should suffice:
GPS orbital altitude: 20,200km (in Medium Earth Orbit, along with GLONASS and Galileo)
Altitude of weather satellite shot down by China: 850km
The technology demonstrated by China only threatens satellites in Low Earth Orbit (up to 2000km, e.g. reconnaissance satellites). Furthermore, GPS has significant redundancy, with (currently) 30 satellites in orbit, so would withstand a degree of attrition.
2. Jamming
As already stated above, GPS is now operating on a greater range of frequencies. The bandwidth of the military frequencies makes jamming a lot harder. Not willing to say anything else!
3. Spoofing (vs airborne platforms only)
Every course I've been on that covers GPS gets round to the subject of spoofing. I don't claim to be an expert on the subject (and a little bit of knowledge can be a dangerous thing
) but you don't need to be a techno-whiz to understand the following:a. Spoofing Individual Receivers
The required process would be to:
a) Determine the current position of the receiver you want to spoof.
b) Calculate what signal that receiver will be getting from each GPS satellite.
c) Calculate what signal the receiver needs to see from each satellite in order to achieve the desired spoofing.
d) Generate and transmit those signals, complete with the appropriate P(Y) and M-code encryptions.
Only the targeted receiver would actually be spoofed. The "bespoke" signals would make no sense to any other receiver in the area and would be rejected.
b. Wide-area Spoofing
This time, the spoofing needs to apply "credible" modifications to the GPS signal, appearing "robust" to all possible users in an area. These modifications would have to be different in different geographical areas - spoofing 100m to the West requires different signals in Kabul and Kandahar, for example.
c. Kalman-filtered GPS / LINS (and TERPROM)
As already observed by a previous poster, the integration of GPS and LINS in one box is what's really at the heart of the revolution in navigation (not least the re-titling of Navigators as WSOs!). Short-term and localised disturbance to GPS has no effect on navigational accuracy of these systems. Longer-term disturbance may well cause degradation. However, the wannabe GPS spoofer now has to tailor his spoofing to sneak beneath the threshold of the Kalman filter lurking within all these boxes. Otherwise, Mr. Kalman will ignore the GPS inputs and warn the system that something is amiss. In a cruise missile, this might prompt reversion to TERPROM navigation. In a UAV or manned aircraft, it would prompt a crew to carry out a reversionary attack (laser-guided, perhaps) or take a navigational fix using traditional methods. Or, if the LINS is good enough, continue navigating inertially until clear of the spoofing. Platforms such as F-15 can already target inertially-guided munitions using synthetic aperture radar pictures.
Spoofing (vs air platforms) summary - virtually impossible to achieve against a single receiver, let alone across a wide area. Even if it could be achieved, largely pointless, thanks to modern kit. The story might be a bit different against ground-based, slow moving receivers, but someone else might be able to provide more detail.a) Determine the current position of the receiver you want to spoof.
b) Calculate what signal that receiver will be getting from each GPS satellite.
c) Calculate what signal the receiver needs to see from each satellite in order to achieve the desired spoofing.
d) Generate and transmit those signals, complete with the appropriate P(Y) and M-code encryptions.
Only the targeted receiver would actually be spoofed. The "bespoke" signals would make no sense to any other receiver in the area and would be rejected.
b. Wide-area Spoofing
This time, the spoofing needs to apply "credible" modifications to the GPS signal, appearing "robust" to all possible users in an area. These modifications would have to be different in different geographical areas - spoofing 100m to the West requires different signals in Kabul and Kandahar, for example.
c. Kalman-filtered GPS / LINS (and TERPROM)
As already observed by a previous poster, the integration of GPS and LINS in one box is what's really at the heart of the revolution in navigation (not least the re-titling of Navigators as WSOs!). Short-term and localised disturbance to GPS has no effect on navigational accuracy of these systems. Longer-term disturbance may well cause degradation. However, the wannabe GPS spoofer now has to tailor his spoofing to sneak beneath the threshold of the Kalman filter lurking within all these boxes. Otherwise, Mr. Kalman will ignore the GPS inputs and warn the system that something is amiss. In a cruise missile, this might prompt reversion to TERPROM navigation. In a UAV or manned aircraft, it would prompt a crew to carry out a reversionary attack (laser-guided, perhaps) or take a navigational fix using traditional methods. Or, if the LINS is good enough, continue navigating inertially until clear of the spoofing. Platforms such as F-15 can already target inertially-guided munitions using synthetic aperture radar pictures.
Controlled Radiation Pattern Antennae (CRPA) provide a further robust antidote to both jamming and spoofing. Google can provide more details for you and then I don't have to tread a fine line of classification.
Anyway, in summary, I don't feel like I need to dust down the old sextant or Dalton computer just yet. Perhaps the General's statement is just designed to keep would-be jammers and spoofers spending money on developing ineffective countermeasures...
Join Date: Jul 2008
Location: New Zealand
Age: 54
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Exactly, why UAVs are in many ways a step backwards...
I have to agree! but not just for GPS issues..
- UAVs in many areas are not being exploited well at all. I see miniature UAVs (4-6kg) being written off because the are small, yet they are a technology that will have huge potential, especially with fuel cell technology around the corner. There's not the $ going into this sector that there should be. I know of only two miniature UAV that have a reliable and robust inertial environment that works with GPS failure. I have had one GPS failure in flight and the INS worked as advertised.
- There also other issues such as the obvious one of airspace integration, but also cost - yes beleive it or not there are some manned platforms that are actually cheaper to run in some functions! sort of flys in the face of the four Ds of UAV employment (Dull Dumb Dirty Dangerous) I note with interest alot of back-flow of UAV technology into manned aviation which is great.
- ISR is always naffed by weather, but UAV platforms are are more at risk due to lack of redundancy and defences. The industy has a long way to go on this. Although larger HALE MALE systems Reaper etc have largely gone through this, ask your friendly tactical UAV guy(or gal) if they have pitot-heat or leading edge de-icing. We are not always going to be operating in the desert. I wonder how well some Isreali UAVs work in Alaska, Falklands, Korea etc. I recall having a big argument with them that in some parts of the world there is wind at night. They didnt beleive me until that night...we need to remember the Isrealis are not an expeditionary defence force nor is their defence industry truley global in it's focus.
Lasty I have seen results from GPS jamming of UAVs it doesnt really work too well. The real Archilles heal is the UAV command link to the GCS, or the GCS itself.
Join Date: Jan 2008
Location: Glasgow
Age: 61
Posts: 909
Likes: 0
Received 0 Likes
on
0 Posts
All navigation systems have problems. You just have to apportion risk to each one and pick the best mix. Here comes a very simplified list. Allocate your own risk, severity and extent.
1/ Ground based radio nav have issues with terrain masking and are even easier to destroy than space based systems. also spoofing & jamming
2/ Space based radio nav systems suffer from earth mask a, are relatively hard to destroy but suffer from spoofing & jamming. Time has an effect on current systems
3/ INS. effected by gravity, magnetic fields and loss of accuracy with distance. Spoofing difficult
4/ Light based systems suffer from earth masking, spoofing and receiver issues. Ground based light emitters easily destroyed
5/ Map matching based systems suffer from data accuracy of maps, season changes, tides, river changes, man made changes, camouflage
6/ Human nav systems depend upon local knowledge and have plenty of issues
7/ Acoustic based systems suffer from ground/ earth masking, temperature fluctuations along path, meteorological effects and interference and spoofing
8/ Compasses. Well. Don't ask. Field fluctuations, gravity, material effects, electrical effects etc. etc. etc.
9/ Politics effects all of them, as does the wealth of a nation and desire to spend.
Have I missed any thing? There is no system that does not have issues. At any one time one might have superiority over another in a given situation. I guess the USA is playing at politics and control at the moment.
Hval
Edited for missing capital letter.
1/ Ground based radio nav have issues with terrain masking and are even easier to destroy than space based systems. also spoofing & jamming
2/ Space based radio nav systems suffer from earth mask a, are relatively hard to destroy but suffer from spoofing & jamming. Time has an effect on current systems
3/ INS. effected by gravity, magnetic fields and loss of accuracy with distance. Spoofing difficult
4/ Light based systems suffer from earth masking, spoofing and receiver issues. Ground based light emitters easily destroyed
5/ Map matching based systems suffer from data accuracy of maps, season changes, tides, river changes, man made changes, camouflage
6/ Human nav systems depend upon local knowledge and have plenty of issues
7/ Acoustic based systems suffer from ground/ earth masking, temperature fluctuations along path, meteorological effects and interference and spoofing
8/ Compasses. Well. Don't ask. Field fluctuations, gravity, material effects, electrical effects etc. etc. etc.
9/ Politics effects all of them, as does the wealth of a nation and desire to spend.
Have I missed any thing? There is no system that does not have issues. At any one time one might have superiority over another in a given situation. I guess the USA is playing at politics and control at the moment.
Hval
Edited for missing capital letter.
I don't own this space under my name. I should have leased it while I still could
There is a conference on GPS vulnerability next month, see below: If anyone want to know more I have a link.
1.2 GPS Jamming & Interference - A Clear and Present Danger
Date: 23 February 2010
Location: National Physical Laboratory, Teddington, Middlesex A one-day conference being organised by the Digital Systems KTN, Location & Timing Programme, in partnership with the Royal Institute of Navigation.
This conference will bring together experts from all aspects of the PNT community to debate important aspects of GPS vulnerabilities including intentional and unintentional jamming, natural and man-made interference and other issues which might impact users and applications which leverage PNT technology.
Multiple and diverse navigational inputs will reduce the susceptibility of a platform to spoofing. An aerial platform with ground mapping radar etc etc will be better placed than a surface platform that has no recognisable terrain for fixing. Spoofing does not have to be massive; indeed a very small degree of spoofing will be sufficient to increase a CEP yet remain undetectable to a kalman filter.
BEagle refers to the ability of a car GPS to maintain a track in a tunnel. Navigon now make such ability clear in their software whereas my TomTom will show a significant error after a Dartford crossing. This of course applies in the case of signal loss not spoofing.
The most vulnerable target, and profitable from an enemy perspective has to be the weapon. The simpler the weapon the greater its susceptibility and the less susceptible the greater the cost. I would hazard a guess that a GPS-Guided PW bomb would be an example of a vulnerable target. You don't need wide-area coverage nor do you need to induce massive errors. Errors in the order of 200-400 yards would be sufficient to make some CAS too dangerous for own forces and for other attacks to have too greater potential for unacceptable colatteral damage.
It is the thought that counts.
1.2 GPS Jamming & Interference - A Clear and Present Danger
Date: 23 February 2010
Location: National Physical Laboratory, Teddington, Middlesex A one-day conference being organised by the Digital Systems KTN, Location & Timing Programme, in partnership with the Royal Institute of Navigation.
This conference will bring together experts from all aspects of the PNT community to debate important aspects of GPS vulnerabilities including intentional and unintentional jamming, natural and man-made interference and other issues which might impact users and applications which leverage PNT technology.
Multiple and diverse navigational inputs will reduce the susceptibility of a platform to spoofing. An aerial platform with ground mapping radar etc etc will be better placed than a surface platform that has no recognisable terrain for fixing. Spoofing does not have to be massive; indeed a very small degree of spoofing will be sufficient to increase a CEP yet remain undetectable to a kalman filter.
BEagle refers to the ability of a car GPS to maintain a track in a tunnel. Navigon now make such ability clear in their software whereas my TomTom will show a significant error after a Dartford crossing. This of course applies in the case of signal loss not spoofing.
The most vulnerable target, and profitable from an enemy perspective has to be the weapon. The simpler the weapon the greater its susceptibility and the less susceptible the greater the cost. I would hazard a guess that a GPS-Guided PW bomb would be an example of a vulnerable target. You don't need wide-area coverage nor do you need to induce massive errors. Errors in the order of 200-400 yards would be sufficient to make some CAS too dangerous for own forces and for other attacks to have too greater potential for unacceptable colatteral damage.
It is the thought that counts.
