The South Korean and U.S. air forces will launch their regular joint military exercise this week to sharpen their combined defense ability, the South Korean military said Thursday.

The twice-a-year aerial exercise, Max Thunder, was first launched in 2008 between the two countries' air forces to foster their joint training against potential North Korean threats. The upcoming drill is the two allies' second Max Thunder exercise this year, following the first one carried out in April.

This year's exercise, to be launched on Friday for a nine-day run at the U.S. air base at Gunsan, 274 kilometers southwest of Seoul, will involve around 90 South Korean and U.S. fighter jets as well as 1,200 military servicemen from the two nations. 

Participating forces plan to carry out a simulation of an aerial battle and air strikes as part of their air defense training during the exercise, according to the military. 

"Ahead of the fourth anniversary of (North Korea's) shelling and provocations on Yeonpyeong Island, the forces will solidify their war readiness through actual war-like training in order to prevent a repetition of the tragedy," Air Force Colonel Cho Deok-gu said. 

Max Thunder is one of a handful of joint South Korea-U.S. military exercises conducted regularly on and near the Korean Peninsula.

North Korea often denounces such joint drills as preludes to the allies' war with the North.

About 28,500 U.S. troops are stationed in South Korea, a legacy of the 1950-53 Korean War, which ended in a cease-fire not a peace treaty. (Yonhap)