File photo of Global Hawk [Photo/CFP]

SEOUL -?The Republic of?Korea planned to buy four Global Hawks, the unmanned spy drone, from the United States to beef up its defense capabilities against possible missile and nuclear threats from the Democratic People's Republic of Korea (DPRK), Yonhap News Agency reported on Friday.

Seoul planned to buy the high-altitude, long-endurance unmanned aerial vehicles (UAVs) through the US Foreign Military Sale (FMS) program, or the government-to-government contract, according to an official of the Defense Acquisition Program Administration (DAPA) cited by Yonhap.

If Washington sends the letter of acceptance (LOA) to the defense procurement agency within this year, the DAPA would start the buying process in early 2014, the official said. If finally decided, a total of four RQ-4 Block 30s, usually called Global Hawk, will be deployed on the Korean Peninsula by 2017.

The Global Hawk is an UAV surveillance aircraft designed by the US-based Northrop Grumman. It can survey as much as 3,000 km, while flying for up to 42 hours at a time at an altitude of 20 km.

The purchase plan came as part of efforts to establish the so-called kill chain system, which preemptively detects and intercepts missile and nuclear threats from Pyongyang.

Seoul and Washington agreed in early October to take preemptive measures if signs of the DPRK's nuclear strikes are detected.