China and the Philippines traded accusations over an encounter in the South China Sea, extending weeks of heightened tension. Beijing said its coast guard identified five Philippine personnel who landed on Sandy Cay, calling the move “illegal.” Manila, meanwhile, said it would dispatch ships to drive away Chinese vessels it described as conducting illegal research. The standoff centers on Sandy Cay, an unoccupied sandbar contested by both countries. Chinese and Philippine officials did not immediately provide further comment on the claims.