Operation Thunderbolt, also known in China as the Defensive Battle of the Han River Southern Bank (Chinese: 汉江南岸防御战; pinyin: Hàn Jiāng Nán Àn Fáng Yù Zhàn), was a US offensive during the Korean War. It represented the first offensive under the new commanding officer of the 8th US Army, General Matthew Ridgway. It started less than three weeks after the Chinese Third Phase Campaign had forced UN forces south of Seoul.