SEOUL - North Korea has been trying since March 4 to jam mobile phones in the Seoul area, as well as GPS tracking devices used by South Korean troops, government and intelligence authorities here said.
The North is believed to be conducting trials of its truck-mounted GPS jamming equipment, allegedly modified from Russian ones, according to the sources, amid high tension over the ongoing joint command post/field training exercises by South Korean and U.S. forces.
The local Munwha Broadcasting Corporation, or MBC, reported the General Bureau of Surveillance of the North Korean People's Army, blamed for the deadly sinking of South Korea's Cheonan warship last year, was behind the latest attempt to block South Korean communication devices.
Col. Yoon Won-shik at the public affairs office of South Korea's Ministry of National Defense declined to comment on the report, and whether or not the GPS-jamming signals were sent by the North.
Yoon said, however, his ministry "has already recognized the North's intent to develop its technology used in blocking GPS signals in the South."
According to the Korea Communications Commission, GPS signals in Seoul and nearby cities, including the western port city of Incheon and Paju near the Military Demarcation Line (MDL) dividing both Koreas, started being disrupted in the afternoon of March 4.
As a result, some mobile phones both used by civilians and soldiers - as well as certain military equipment, such as distance measurement devices in artillery units - in the areas didn't work properly, the commission said.
Some citizens in the areas were still suffering network problems with their cellular phones March 6, it said.
Commission and other government officials believe the GPS-jamming signals were sent from the North's military bases in Haeju and Gaeseong, which are close to the heavily fortified border.
"The signals were sent intermittently every five to 10 minutes, so we suspect the North was testing its new GPS blockers imported from overseas given that the jamming signals were not sent continuously," an unidentified intelligence source said, according to Yonhap news agency.
Damage by the GPS disrupting maneuvers was relatively minor, the official said, adding: "The South Korean government has already been on track to establish an anti-jamming system to control and overcome such a low level of GPS blocking attempts."
In a parliamentary audit of the defense ministry in October 2010, former Defense Minister Kim Tae-young said that the North had already developed a GPS jammer by copying a Russian device.
The jammer is believed to be capable of disrupting all GPS signals in radius of 50 to 100 kilometers (31 to 62 miles), including state-of-the-art missiles and precision bombs.
When the Iraq War began in 2003, the Iraqi army is known to have caused a stir by using a similar GPS jamming system to disrupt the U.S. military's guided weapons systems.
The South Korean military and U.S. Forces Korea (USFK) has boosted their GPS-guided precision striking missiles in recent years.
Since last March, USFK has deployed five new A-10 ground attack jet aircraft that can carry the Joint Direct Attack Munition (JDAM). The South Korean Air Force has also equipped its fleet of KF-16 fighters with JDAMs.
The JDAM can be used in neutralizing North Korea's artillery pieces hidden in mountain caves and tunnels near the border.
The jamming accusations take place as the U.S. and South Korea are conducting joint military exercises. Above, a U.S. soldier sits inside a nuclear, biological and chemical reconnaissance vehicle March 3 at Dongducheon, about 25 miles north of Seoul. (Jung Yeon-Je / Agence France-Presse)
The local Munwha Broadcasting Corporation, or MBC, reported the General Bureau of Surveillance of the North Korean People's Army, blamed for the deadly sinking of South Korea's Cheonan warship last year, was behind the latest attempt to block South Korean communication devices.
Col. Yoon Won-shik at the public affairs office of South Korea's Ministry of National Defense declined to comment on the report, and whether or not the GPS-jamming signals were sent by the North.
Yoon said, however, his ministry "has already recognized the North's intent to develop its technology used in blocking GPS signals in the South."
According to the Korea Communications Commission, GPS signals in Seoul and nearby cities, including the western port city of Incheon and Paju near the Military Demarcation Line (MDL) dividing both Koreas, started being disrupted in the afternoon of March 4.
As a result, some mobile phones both used by civilians and soldiers - as well as certain military equipment, such as distance measurement devices in artillery units - in the areas didn't work properly, the commission said.
Some citizens in the areas were still suffering network problems with their cellular phones March 6, it said.
Commission and other government officials believe the GPS-jamming signals were sent from the North's military bases in Haeju and Gaeseong, which are close to the heavily fortified border.
"The signals were sent intermittently every five to 10 minutes, so we suspect the North was testing its new GPS blockers imported from overseas given that the jamming signals were not sent continuously," an unidentified intelligence source said, according to Yonhap news agency.
Damage by the GPS disrupting maneuvers was relatively minor, the official said, adding: "The South Korean government has already been on track to establish an anti-jamming system to control and overcome such a low level of GPS blocking attempts."
In a parliamentary audit of the defense ministry in October 2010, former Defense Minister Kim Tae-young said that the North had already developed a GPS jammer by copying a Russian device.
The jammer is believed to be capable of disrupting all GPS signals in radius of 50 to 100 kilometers (31 to 62 miles), including state-of-the-art missiles and precision bombs.
When the Iraq War began in 2003, the Iraqi army is known to have caused a stir by using a similar GPS jamming system to disrupt the U.S. military's guided weapons systems.
The South Korean military and U.S. Forces Korea (USFK) has boosted their GPS-guided precision striking missiles in recent years.
Since last March, USFK has deployed five new A-10 ground attack jet aircraft that can carry the Joint Direct Attack Munition (JDAM). The South Korean Air Force has also equipped its fleet of KF-16 fighters with JDAMs.
The JDAM can be used in neutralizing North Korea's artillery pieces hidden in mountain caves and tunnels near the border.
