As stealth fighter jets and naval destroyers can evade radar, they can secretly approach and hit the target without being noticed.

According to a military source on Monday, the Agency for Defense Development (ADD), which began research on stealth technology in 1999, has developed a substance that absorbs electric waves, an essential part of the radar-evading technology.

The ADD, which conducted in utmost secrecy a ground test of an F-4 fighter and a miniature fighter equipped with the material late last year, concluded that the result was satisfactory.

Though military authorities are refusing to reveal details of the material, experts believe it is either paint or a special film that can be applied on jets.

The F-22 and F-35, which are considered the world’s best stealth fighter jets, are coated with a special film that absorbs radar waves.

The ADD and the Air Force are planning a test flight of an F-4 fighter jet equipped with the newly-developed material.

If the aircraft is undetected by radar at the test, the radar evading substance will be allowed to be used for military equipments, including fighter jets.

In addition, the military has also successfully developed part of the technology for designing fighters and destroyers for effective evasion of radar waves.

"Following the United States’ deployment of F-22 fighter jets this year, China, Russia and Japan are also striving to secure stealth technology to apply to their weapons systems with the aim of securing command of the air in Northeast Asia," a military official said. “South Korea will also complete the development of the core technology by the mid-2010s."

However, some critics argue that it will take a very long time before Korea can develop its own stealth fighters or destroyers even after securing the core stealth technology.

Korea plans to purchase 60 fifth-generation stealth fighters, such as F-22s or F-35s, from overseas around 2011 and deploy them from 2014 until 2019 to build up air power.