The K9 Thunder is a South Korean 155 mm self-propelled howitzer designed and developed by the Agency for Defense Development and private corporations including Dongmyeong Heavy Industries, Kia Heavy Industry, Poongsan Corporation, and Samsung Aerospace Industries for the Republic of Korea Armed Forces, and is now manufactured by Hanwha Aerospace.^[3] K9 howitzers operate in groups with the K10 Ammunition Resupply Vehicle variant.^[5][6]

The entire K9 fleet operated by the ROK Armed Forces is now undergoing upgrades to K9A1, and a further upgrade variant K9A2 is being tested for production. As of 2022, the K9 series has had a 52% share of the global self-propelled howitzer market, including wheeled vehicles, since the year 2000.^[5][6]