SEOUL - North Korea's electronic warfare capabilities are second only to Russia and the United States, a South Korean expert claimed Thursday.

Speaking at the Defense Security Command's information security conference in Seoul, professor Lee Dong-hoon of the Korea University Graduate School of Information Security also said that Pyongyang's electronic warfare unit was behind the jamming of GPS signals in South Korea. From April 28 until May 13, GPS signals were jammed here causing difficulties in air and marine traffic controls.

According to Lee, North Korea's Reconnaissance General Bureau was responsible for the GPS jamming.

The Reconnaissance General Bureau was formed in 2009 by combining three organizations with similar functions to oversee espionage and sabotage operations in South Korea and other nations.

Lee also said that the bureau has separate units for cyber attacks on the military, for online psychological warfare conducted against society in general, and for hacking into South Korean organizations.

"North Korea has been preparing for cyber warfare since the late 1980s and is now the third strongest in cyber warfare after Russia and the U.S.," Lee said.

"In North Korea the state nurtures cyber (warfare) personnel to achieve military aims, and is capable of conducting various cyber attacks including denial of service and hacking."

He added that the distributed denial of service, or DDoS, attack in July 2009 is suspected to have been conducted by the Pyongyang Computer Technology University.

In July 2009, 26 South Korean and foreign organizations' websites were affected by DDoS attacks. Of the 26, 11 were local organizations' web sites including that of the presidential office of Cheong Wa Dae, National Assembly, Ministry of National Defense and Shinhan Bank and Korea Exchange Bank.

Regarding the South Korean military, Lee said that much needs to be done to prepare against the threat.

"In contrast, our military only recruits some individuals with telecommunications degrees for cyber defense roles and does not have specialists," Lee said.

"A cyber defense branch needs to be established to systemize cyber attack and defense related duties, and install cyber warfare training and cyber war room facilities."

Concerns over North Korea's cyber warfare capabilities were also voiced by chief of the Defense Security Command Army Lieutenant General Bae Deag-sig.

"North Korea is attempting to use hackers to infiltrate our military's information system to steal military secrets and to incapacitate the defense information system," Bae said.

"The military is updating the information protection policies and systems as part of the efforts to strengthen its response capabilities."