Sultan Qaboos who has ruled Oman for almost half a century is in stable condition after recently travelling to Belgium for a medical checkup, his royal court announced Tuesday. "The sultan is in a stable condition and following a scheduled treatment program," the official ONA news agency cited the royal court as saying, without giving details. The court announced on December 7 that Qaboos, 79, was travelling to Belgium for "a limited period of time", but did not give details on his condition. Qaboos underwent lengthy medical treatment in Germany in March 2015. He has limited his public appearances since then.