By Chung Hee-hyung

More than two weeks have passed since North Korea have sent signals jamming South Korea's GPS communications, affecting scores of civilian flights and vessels traveling in and around the two countries’ borders. Although North Korea ceased to jam the signals from May 14, a government source said the military is still “on alert.”

The reason for the North’s abrupt halt is not clear, but an agreement between the South and China to coordinate steps in dealing with the pariah state’s jamming attack may have played a part.

“The decision of China and South Korea, whose heads of state met in a bilateral summit on May 14, could have influenced North Korea’s decision,” a member of a government think tank said.

The government has cautioned that this may only be a temporary respite. “We are still preparing for the possibility that the North might resume its jamming,” the source said. “The North may also resort to other means of provocation.”

The signals, so far, have been little more than a nuisance; no major accidents or physical damage have yet been reported.

Nonetheless, the disruption could still pose a threat close to the North-South border, albeit to varying degrees. The military employs its own GPS system which uses a different code from civilian ones and is less prone to jamming. Moreover, most aircraft _ military and civilian alike _ are equipped with inertial navigation systems that do not require outside information to calculate their position.

For South Korean fishing vessels, however, it is a different matter. Their navigational systems are far less sophisticated, and without GPS the boats are unable to locate their precise position. It is a source of concern to Lee Jin-gu, head of the local Yeonpyeong Fisheries Association.

“We are forced to search our fishing grounds in looking for of our nets. On foggy days, the visibility is especially poor and this may cause our ships to collide. The boats may even inadvertently find themselves straying into North Korean waters.”

Nor are military aircrafts entirely immune to GPS attacks. Last March, North Korean GPS jamming forced an U.S. RC-7B reconnaissance plane to make an emergency landing just 40 minutes after takeoff while taking part in a joint South Korea-U.S. military exercise.

South Korea, however, is still at a loss of how to cope with this invisible threat. Short of directly attacking the source of the GPS jamming, there are few, if any, effective countermeasure at its disposal.

Since Pyongyang started jamming signals on April 28, Seoul has been powerless to stop the incessant attack apart from sending an official protest letter through the International Civil Aviation Organization (ICAO).

Not that the South has been sitting idly in the face of the Stalinist state’s threat. The South Korean Defense Acquisition Program Administration (DAPA) has been pushing for a scaled-downed version of GPS called Ground Based Navigation System (GBNS).

GBNS is a ground-based alternative which uses transceivers instead of satellites to send and receive positioning information. The system is a poor substitute for GPS, however, partly because it is less accurate, and in any case the Board of Audit and Inspection (BAI) recommended that DAPA discard it.

Last June, local newspaper Naeil reported that the head of the BAI personally met with Defense Minister Kim Kwan-jin and expressed his “concern” to Kim that the project for GBNS might not be feasible.

“The chairman of BAI advised that it would be better to purchase GPS receivers from the United States instead,” said an official from the defense department who attended the meeting. Asked for comments, officials from both agencies said that it was inappropriate to speak on the project’s feasibility while it was still in progress.

In fact, little progress has been made since the BAI’s strong rebuke. “No measures are currently available against North Korea’s GPS jamming,” an anonymous South Korean military source said recently.

In October 2010, then South Korean Defense Minister Kim Tae-young reported to the National Assembly that the North’s GPS jamming was a new type of provocation against which the military was “finding ways” to deal with. Almost 19 months since his remarks, the military has not much to show for its efforts.


The writer is Korea Times intern