Chinese Foreign Minister Wang Yi pointedly remarked that he had been waiting "for more than half an hour" in comments through an interpreter after Kerry arrived late for a meeting between the two countries.
Kerry, chuckling sheepishly, apologised for keeping Beijing's top diplomat waiting.
"I am very, very sorry," he said ahead of the meeting on the sidelines of talks between the Association of Southeast Asian Nations (ASEAN) and regional and global powers.
Wang today said China was not the aggressor in the disputed waters, but vowed Beijing would have "clear and firm reactions" to defend its interests in the sea.
