A US Air Force F-22 Raptor stealth jet flies over a South Korean air base in Gwangju on December 4, 2017 The US and South Korea on December 4 kicked off their largest ever joint air exercise, an operation North Korea has labelled an “all- out provocation”, days after Pyongyang fired its most powerful intercontinental ballistic missile. (Photo by AFP Photo/Yonhap)
