Chinese intercepts of US planes in the South China Sea has been described by the US as “unsafe and unprofessional behavior,” The Wall Street Journal reported, citing a senior US official. The Pentagon made public what it characterized as a particularly aggressive encounter on Tuesday, and US officials said that at least three similarly provocative incidents occurred earlier this year. The incidents mar what has been an unusually cooperative period for the two militaries, though Chinese territorial assertions in the South China Sea have kept nations in the region on edge for over a year. “The Chinese are trying to be more active in establishing good quality military-to-military relations. There’s just something different and unique about what’s going on in the South China Sea,” a senior US official said.