September 13, 2011: The U.S. recently revealed that one of its RC-7C reconnaissance aircraft was forced to land last March 8th, after a North Korean GPS jammer disrupted the aircraft’s navigation system. All that had previously been revealed about this was that, from March 18th onwards, North Korea had been directing a GPS jamming signal across the border, and towards the southern capital, Seoul. The jamming signal could be detected up to a hundred kilometers south of the DMZ. The North Korea GPS jammers are based on known Russian models that North Korea bought and copied. The usual response for 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, and South Korea did not destroy the jammer.

The jamming was more of a nuisance than a threat, and most military equipment is equipped with electronics and other enhancements to defeat it. So it was somewhat surprising that the U.S. would now admit that one of their aircraft was disrupted by the North Korea GPS jammer ten days before this equipment was just aimed in the general direction of South Korea and turned on for a week.

That March incident was the third time in a year that the north had attacked the south. The first was the torpedoing of a South Korean warship in early 2010, then the shelling of a South Korean island off the west coast last November. Then came the GPS jamming last March, followed by DDOS attacks and other Internet based attacks on government websites a few months later.

The North Korea GPS jammer threat has been around for a while. South Korean intelligence has been trying to get their hands on North Korea's new GPS jammer for over three years. These items are used to spoil the aim of GPS guided bombs and missiles, as well as disrupt other navigation systems, in wartime. The U.S., NATO, Israel and several Middle Eastern nations (friendly to the U.S.) are big users of such guided weapons. The North Korean jammer has been offered to Middle Eastern Nations (as in Syria, Iran and Hezbollah), and is touted as superior to the Russian model (which Iraq had, and used, without much success, in 2003). The Russians have since improved their technology, but the U.S. believes its anti-jammer devices are capable to dealing with the new Russian gear. One is never sure unless you can test the anti-jammer technology against the jammer. Thus the eagerness to get a North Korean jammer into the hands of U.S. Air Force anti-jammer experts for examination. Until last March, many GPS experts doubted that the North Korean jammer actually existed, as the North Korean have never exhibited much talent in that area of technology. That attitude has changed somewhat, but it’s still a mystery why the North Koreans would reveal their capabilities just like that. What makes the March incident ominous is that there were reports, from some refugees that the north was working on jammers with longer range and even more power.