In case you were wondering what this relates to, it is due to Japan moving forward with their decision to release the treated radioactive water from the Fukushima power plant into the ocean - which also starts today. The move has received plenty of backlash in the international community as the optics looks terrible, but the science behind it is actually rather sound.
But as you can imagine, there will be trust issues regarding the safety and efficacy of such a move. And it looks like China, among other nations, are not willing to take on that risk.