South China Sea tensions: China, Philippines trade accusations on illegal landings, covert research

There has been a renewal of tensions in the South China Sea, in the thick of joint military drills between the US and the Philippines. China is accusing Philippine troops of landing illegally in a disputed sandbar that is unoccupied. It is unclear if Beijing took any further action. Sandy Cay is close to Thitu Island - referred to as Pag-asa Island by Manila - in the Spratlys.