North Korea has significantly beefed up its human resources to boost its cyber warfare capabilities, the South Korean military said Sunday.

"A total of 6,800 hackers -- some 1,700 experts and 5,100 supportive members -- have been assigned to hacking and other cyber provocations," a senior military officer told reporters, requesting anonymity.

The latest figure is 900 more than what Seoul's Military Cyber Command reported to the National Assembly in October.

"North Korea appears to have been concentrating on boosting its ability to launch online warfare as one of the core asymmetric capabilities, along with nuclear and missile programs," the officer said.

The North is believed to be linked to a series of leaks of data on South Korea's nuclear power plants in December. The U.S. has also accused Pyongyang of being behind the hacking of Sony Pictures in November over its comedy film "The Interview," which depicts a plot to assassinate North Korean leader Kim Jong-un.

In the wake of growing security threats online, South Korea has decided to drop its long-held defensive tactics in cyber warfare and instead initiate proactive operations.

To better guard against enemies' online infiltrations, it is pushing to establish a new team in charge of cyber operations under the Joint Chiefs of Staff (JCS) while increasing its personnel from the current 600 to 1,000.

Meanwhile, the communist North is believed to have dispatched an increased number of anti-aircraft guns and established wind vanes along the western and central border regions in a move to counter propaganda leaflets floated by South Korean civic groups.

The North has long bashed the South for not preventing its civic activists from sending anti-Pyongyang leaflets that criticize the North Korean regime across the border, and vowed harsh retaliation against such moves.

Despite Pyongyang's repeated calls, the Seoul government has maintained it cannot stop the cross-border campaigns, citing the groups' freedom of speech.

"North Korea has continued to stage drills against the balloons by mobilizing anti-aircraft, anti-tank guns and artillery troops, according to our analysis," the Seoul officer said, noting that the South Korean military has been closely watching their movements.

In October, the two Koreas exchanged machine gun fire across the tense border, after the North apparently tried to shoot down balloons carrying propaganda leaflets flown from the South. (Yonhap)