A picture taken on March 10, 2016 shows paratroopers during the Northern Thunder military exercises in Hafr al-Batin, 500 kilometres north-east of the Saudi Capital Riyadh. Warplanes roared overhead, tanks rumbled across the desert and smoke filled the sky for the final day of what Saudi Arabia billed as the region’s biggest-ever military exercises. The 12-day “Northern Thunder” manoeuvres in the kingdom’s northeast included 20 nations from the Middle East, Africa and Asia, Saudi officials said.