The air force will inject 12 trillion won to independently develop KF-X fighter jets by 2018.

Military sources said Monday that the Agency for Defense Development will produce some 40 KF-X fighters. KF-X fighters are a grade below F-X models.

As a result, the military by 2020 will have 420 high and low fighter jets including KF-16s, F-15Ks, KF-Xs and A-50s.

The air force will deploy 40 F-15Ks by 2008 and invest five trillion won into the F-X project from 2009 to 2015 to add 40 more jets, doubling its air fighting power.