February 2, 2020: In early January the U.S. Navy again told the FAA (Federal Aviation Authority) that the navy would once more be conducting a carrier task force training exercise off the southeast American coast that would involve GPS jamming. These exercises ran from the 17th to the 24th and the jamming was scheduled to last several hours a day. The FAA then sent an “advisory” out to commercial and private aviation, as well as ships informing of the days and times of the jamming with information on how to cope and a request to report GPS disruption encountered, including times and the impact. After the 2019 exercise, 1,230 reports were sent in, via an electronic form and 64 percent of then noted serious problems with their navigation equipment. In some cases, the equipment did not return to normal until after the aircraft landed.

Similar exercises have been conducted, and FAA advisories issued, for exercises at some land-based weapons testing areas as well as army and air force bases. These exercises have been going on for several decades but usually involve less powerful, and shorter-range jammers. The January exercises south of  Norfolk involved wide-area jamming similar to what warships would encounter on the high seas. The worst impact is in a relatively small area but the navy warns that some jamming could have a lesser impact up to 700 kilometers away from the jammer. These wide-area navy jamming exercises have been going on for several years now and are considered a necessary part of training as well as a way to test existing procedures and equipment designed to deal with such jamming.

The navy can refer to these complaint reports to determine the impact of jamming on civilians. Firms that manufacture navigation equipment find these exercises a useful way to determine the wartime impact of such jamming

It is more common for nations using GPS jamming gear to keep quiet about it, especially those nations that use the jammers unexpectedly in peacetime. Over the last few years, there has been growing evidence that Russia has been frequently jamming or spoofing (deceiving) GPS signals, mainly to hide the exact location of key people or military units. Developing equipment like this is easily within Russian capabilities.

In early 2019 a civilian think-tank (C4ADS) released a report in which they described how they had found nearly 10,000 instances that someone, apparently Russia, had been jamming or spoofing satellite navigation signals. Not just the American GPS, but also signals from non-American satellite navigation systems (Chinese Beidou, EU’s Galileo, Japan’s QZAA and even the Russian GLONASS). Much of this activity was not outright jamming but spoofing. This was apparently done to conceal the true location of key Russian officials (like president Putin) and Russian military units. The spoofing was particularly common for Russian military forces in Ukraine and Syria. The spoofing replaced the actual satellite signal with a false one that rendered smart bombs or planned attacks on targets inaccurate.

Spoofing has become more popular and practical because it does not require expensive or high-tech equipment. While American weapons and military navigation systems have a backup in the form of unjammable INS (Internal Navigation System) systems, these are useless if the spoofing is not detected so the INS can take over. American systems are supposed to detect spoofing and revert to INS but the Americans do not disclose details of how these systems work in order to make it difficult for spoofing systems to be modified to be less detectable. That is one reason why the U.S. has not released information on spoofing incidents.

To further complicate matters there have also been instances where ship AIS (Automatic Identification System) transponders were spoofed. By international law, all large seagoing ships were required to carry and use AIS equipment, which constantly broadcast the GPS position of the ship. But there were cases where ships suddenly saw the AIS positions of ships near them change because, it turned out, someone was spoofing GPS signals in the area using a short-range jammer.

AIS equipment is designed to report when it was getting no GPS signal at all. Large ships usually carry two AIS units, in case one malfunctions. Jammers attempt to disrupt AIS by just introducing a more powerful but inaccurate GPS signal. But in these cases, the spoofing does not work as intended and some ships would receive no signal at all, which causes an alarm to go off.

Other nations are not as secretive in complaining and often the culprit is Russia. In late 2018 Finland and Norway went public with their accusations that Russia deliberately jammed GPS signals in northern Finland and Norway from a location near the Russian military bases in the Kola Peninsula on the Barents Sea. The jamming took place as NATO held its largest training exercise since the Cold War ended in 1991. Russia denied any responsibility even though they are known to possess long-range jammers for GPS and other signals. Norway said they had tracked the jammer to a specific location but when Russia refused to admit any involvement Norway refused to explain how they tracked the signal because that would provide Russia with information on Norwegian EW (Electronic Warfare) equipment that might be useful to them.

What was curious about this incident was that it had no impact on the NATO military exercises and even commercial airliners operating in the area had backup (INS) systems in case GPS signals were not working properly. The potential victims were civilians with smaller aircraft or on the ground who depend on commercial navigation gear using GPS. Then again, that may have been the point because Russian firms have long been producing a wide variety of GPS jammers that are generally ineffective against military GPS users but would be useful for criminals, terrorists or anyone involved in irregular warfare, as Russia has been in Ukraine since 2014. As for the damage to diplomatic relations with Norway and Finland, these two nations need no reminders of what a bad neighbor Russia is and historically has been. C4ADS analysts concluded that the Russian spoofing incidents were possibly common practice whenever president Putin traveled, probably as a security measure to render assassination attempts using UAVs armed with explosives. This has become a common tactic with Islamic terrorists, who consider Putin a prime target for UAV attacks. This new Russian jammer was not a surprise. Russia was a major developer of such gear during the Cold War and kept at it after the Cold War ended in 1991.

By 2010 the U.S. Department of Defense was spending a lot of money on developing a jam-resistant replacement, or backup (depending on who you talk to), for GPS. The best candidate was an improved INS, which has existed for nearly a century but since the 1960s had gotten smaller, cheaper, and more reliable as electronic components did the same. Basically, INS uses three gyroscopes and three accelerometers to constantly measure changes in direction and changes in velocity. With that, the INS will always know where it is in relation to its initial starting point (which can be obtained initially via unjammed GPS or older means). Miniature INS devices have long served as a backup for GPS guided weapons. But while GPS guidance can land a bomb or missile within 10 meters (32 feet) of a target, INS can only achieve 30 meter accuracy. GPS also has the advantage of not needing to have its exact position entered after the INS is turned on. On the upside, that means INS cannot be jammed or spoofed. These micro- gyroscopes and accelerometers have become standard in many smartphones to not only detect orientation but also movement. The use of this tech by smartphone makers resulted in even cheaper and more reliable designs that proved very useful for military INS backups for GPS.

After 2010 American researchers created new concepts and technology that could greatly improve current INS accuracy and cost. By 2013 prototypes proved they could be nearly as accurate as GPS and almost as small. The cost was still a factor, with the new INS still costing more than 10 times what GPS does. But this is all a big improvement over what has been available before. The new INS can now be used to monitor GPS and alert the operator that their GPS has either developed a problem or is being jammed. The new INS is also useful for some fast missiles that often lose their GPS signal as they maneuver. Another urgent chore for INS is to alert users that their GPS is being spoofed (sent a false signal that is luring the user away). Thus, even with the ability of anti-jamming tech to keep up with jammer technology, there is still a demand for a new INS. That has led to smaller, cheaper and more accurate INS systems. Aside from airlines and commercial shipping, there is not much of a mass market for these new INS systems because for most consumers GPS is reliable enough to keep the INS gear out of the consumer market. But the demand from the airlines, shipping companies and the military is huge. However the tech remains popular for smartphones and other consumer items, but not as INS. That is changing as some smartphone (and smartwatch) manufacturers seek to use INS to automatically fill in if the user temporarily loses the GPS signal.

Many Department of Defense navigation and electronics experts believe current anti-jamming efforts are sufficient to keep military GPS use viable, but the new INS technology has attracted a lot of attention in the military as backups are always appreciated because when equipment fails in combat it’s literally a matter of life or death. Meanwhile, the U.S. is building and testing more compact GPS anti-jamming systems for smaller (as small as 200 kg/440 pounds) UAVs. This is part of a program to equip all American UAVs, even the smallest ones, with more secure GPS. While all UAVs can be “flown” by the operator, the GPS makes it a lot easier for the operator to keep track of exactly where his UAV is at all times and sometimes the UAV is programmed to simply patrol between a series of GPS coordinates. If the GPS jams or fails the operator can usually use the video feed to find landmarks on the ground and bring the UAV back to where it can be seen and landed.

While American troops have not yet encountered much (if any) battlefield GPS jamming, the threat exists. Currently, American troops can experience this sort of thing in Ukraine (where NATO nations have military advisors and observers) and Syria. This jamming tech is also showing up in Iraq and Afghanistan. Before that, the most tangible evidence of this came from North Korea, which has long made, sold, and itself used GPS jammers. In 2012 North Korea attacked South Korea with a massive GPS jamming campaign. The jamming began in late April and continued for over two weeks. It took less than a day to confirm that the signal was coming from North Korea and was mainly aimed at the South Korean capital (Seoul). The jamming had little impact inside the city itself (the ground-based jamming signal was blocked by buildings and hills) and was only noted by several hundred aircraft landing or taking off from local airports and over a hundred ships operating off the coast. In all these cases the ships and aircraft had backup navigation systems, which were switched on when GPS became unreliable. This is how navigation systems, especially those that rely on an external (satellite) signal, are designed.

The 2012 incident was the third time North Korea has used GPS jamming against South Korea. For most of March 2011, North Korea directed a GPS jamming signal across the border towards Seoul. A separate jammer has been directed at cell phone traffic. The GPS jamming signal could be detected up to a hundred kilometers south of the DMZ.

The usual response to GPS jamming is to bomb the jammers, which are easy to find (jamming is nothing more than broadcasting a more powerful version of the frequency you want to interfere with). But such a response could lead to more fighting in Korea, so the south protested and refrained from responding with force. The jamming was a nuisance more than a threat and most military equipment is equipped with electronics and other enhancements to defeat it. The North Korean jamming confirmed what was already suspected. So now South Korean and American electronic warfare experts have an opportunity to study the effects of jamming on a large metropolitan area. It caused intermittent problems for users of GPS devices and many more cell phone connectivity problems. There were briefer and less powerful jamming incidents in August and December of 2010.

China and Russia are both selling GPS jammers. In 2007, China brought to market a powerful truck-mounted GPS jamming system. These "GPS jamming vans" are meant to create a protective "bubble" over an area the van is in the middle of. A year before the 2003 invasion of Iraq it was believed that Saddam had bought many GPS jammers to deal with U.S. JDAM GPS smart bombs. The JDAM has a backup INS, which was no secret, and the Iraqi GPS jamming efforts had no significant effect on the 2003 campaign.

There are several approaches to defeating GPS jamming, and knowing which one each American GPS guided weapon uses makes it easy to develop a way to jam the "jam-proof" GPS. The U.S. Air Force is understandably reluctant to discuss what they are doing. Given the cost of jam proofing all existing GPS weapons, it's more likely that jam-proof GPS weapons will only be used against targets where the GPS accuracy is vital. Against most targets, the accuracy provided by the inertial guidance system will do. Also, note that you can bomb GPS jammers with a bomb equipped with a guidance system that homes in on a GPS jamming signal. For that reason, it's thought that any use of GPS jammers will involve dozens of jammers in each area so protected. The GPS jamming has no effect on the even more accurate laser-guided bombs, and some countries buy smart bombs with both laser and GPS/INS systems. Most countries are working on anti-jamming tech in anticipation of encountering more jamming if war comes.