Two new F-35A stealth fighter jets will arrive here from the U.S. in late March. The Air Force hopes to deploy about 10 of them warfare-ready this year.
The Air Force took delivery of six of them at a plant in Fort Worth, Texas last year, but pilots have been undergoing training at Luke Air Force Base in Arizona before they are brought to South Korea.
The project encompasses a total of 40 of the jets and will cost W7.4 trillion until it is completed in 2021 (US$1=W1,116).
The jets fly at a top speed of Mach 1.6 and have a range of 2,170 km, carrying up to 8.2 tons of missiles and bombs.
They are a key part of the South Korea's "kill chain" defense against North Korea's nuclear and missile bases and mobile missile launchers.
Japan already deployed about 10 F-35As last year and plans to buy 147 of them. China began deploying homegrown J-20 stealth fighter jets last year.
But the government here is worried that North Korea will react sensitively to their deployment. Pyongyang denounced last year's handover ceremony in Texas as "a criminal act against the nation."