According to a source in the South Korean government since May 2012 North Korea has deployed about 20 helicopters at 2-bases located in the vicinity of a specific South Korean island of Baengnyeong. Helicopters, among which, as noted E-2 E-4 and E-8 Russian production, equipped with machine guns and rocket launchers.
South Korea, for its part, is ready to counter the alleged attacks using rockets "ground-to-air" also considering options for deployment in the border area F-16 fighters, if the helicopter group DPRK in the region will increase.
As the "Chosun Ilbo", after the arrival of Kim Jong-un to power in December 2011, the army DPRK showed a significantly higher activity and conducted large-scale exercises near the border with South Korea, that perhaps could be made in anticipation of the planned cross-border attacks on Seoul.
The agency "Yonhap", in turn, confirms the information about the deployed near the border of North Korean helicopter, but his government sources estimate the number of air vehicles at about 50 pieces.
As recalls Agence France-Presse, border inter with 2 Koreas already became a place of violent clashes in 1999, 2002 and 2009. In 2010, North Korea shelled the South Korean peninsula Ephendo that led to the death of two fighter. After the incident, the parties exchanged threats, but it's up to them to implement it never came.