South Korea said it favors a joint U.S-Korean missile defense system rather than the United States-led plan involving the purchase of longer range missiles.

South Korea's anti-missile system, under the Korea Air Missile Defense program, is designed to protect the south from short-range missiles fired by North Korea while the U.S. system uses missiles to protect against medium- and long-range ballistic missile threats.

"South Korea and the U.S. will discuss intelligence sharing and operation of means regarding the missile defense system so as to protect the Korean Peninsula from the threats of North Korean nuclear weapons and its weapons of mass destruction at the Extended Deterrence Policy Committee," the ministry said in a statement.

"This does not mean that we will join the U.S. missile defense system. This means we will strengthen cooperation with the U.S. Forces Korea in the sharing of intelligence and operation of available assets to effectively respond to threats from North Korean ballistic missiles."

North Korea has short-range Scud and Rodong missiles with a range of around 850 miles and is thought to be developing longer-range Taepodong missiles that could reach the United States. The Taepodong-2, which on paper has the ability to reach the nearest Alaskan shore, was test-launched in 2006 but blew up after a flight of less than a minute.

Seoul has been careful about choosing its missile defense options for fear of antagonizing China, a staunch ally of North Korea. Any decision to acquire longer range missiles that also could reach Chinese cities might seriously ramp up military tensions in the region.

North and South Korea are still technically at war after a 1953 cease-fire drew a demilitarized border along the 38th parallel across the peninsula.

Disputes over land frontiers and maritime boundaries are common. But tensions on the peninsula reached near unprecedented heights last March when Seoul blamed North Korea for sinking its naval patrol boat the Cheonan, with the loss of 46 sailors. North Korea denied it was involved.

As late as last June, South Korea was considering purchasing more Patriot missiles as an anti-missile defense against North Korea. However, the Ministry of Defense said it was considering only a land-launch version of Raytheon's Patriot Advanced Capability 3 system and wouldn't deploy them on warships, move that potentially would bring the missiles within firing range of China.

In early 2009 South Korea began planning in earnest its own missile defense system to be operational within three years against North Korea.

The 2009 announcement came amid Pyongyang's latest test-launch preparations for its ballistic missiles.

The South Korean Ministry of Defense said it would set up an air defense unit solely for the detection and interception of North Korean ballistic missiles by 2012.

The ministry estimated it would need to spend around $214 million on the project, including radar systems, that had been mooted since 2006.

By 2007 the Defense Acquisition Program Administration approved a $1 billion SAM-X project to purchase 48 second-hand PAC-2 launch modules, radars and missiles, including the Patriot anti-tactical missile and guidance enhanced missile plus from Germany.

The agency also signed a contract to buy ground-control equipment from Raytheon of the United States to support two Patriot system battalions. A battalion is usually made up of three units, each of which has eight missile launchers and a command center.