How borders are drawn and enforced has far-reaching consequences, whether we live on either side of them or halfway across the world.

China’s not one to sit by idly when it feels it’s been wronged.

So when South Korea agreed to let the US implement a missile-defense shield in the country, China appeared to respond by restricting Korean pop culture in the mainland. This crackdown on Korean dramas and pop music may have started as early as August, but South Korea only publicly commented on the matter two days ago (Nov. 28).

Up until recently, most of the news pertaining to China’s tightening of Korean culture had come from South Korea’s state-run Yonhap News Agency. Reports say China has turned down Korean stars’ applications to perform in the country and that it has not let any Korean movies screen in the mainland (link in Chinese) this year. China has been the one of largest markets for Korean pop culture (link in Chinese) in the last decade, investing $275 million in Korean publications and broadcasting in 2015 alone.

China, for its part, maintains it’s unaware of such restrictions. ”I have never heard about any restriction on the Republic of Korea,” said China’s foreign ministry spokesperson Geng Shuang in a press conference on Nov. 21. While Geng denied the tightening was an official move responding to the missile-defense system, he said “the Chinese public has voiced their dissatisfaction as well.”

Not all are buying it. On the social media platform Weibo, one commenter said (link in Chinese): “Honestly, I really love Korean entertainment shows, but there is no idol when it comes to China’s sovereignty matter, everything could be gone in a blink of an eye.”

The drama started in October when South Korea (link in Chinese) noticed that none of its stars had obtained Beijing’s permission to perform in the country that month. In contrast, nine performances by Korean stars were approved from July to September.

Then, in November, Japanese bank Nomura told the Financial Times that Chinese authorities seemed to have banned (paywall) broadcasting of TV programs and advertising featuring Korean artists and brands.

A Chinese company was also penalized 100,000 yuan ($14,500) this month (link in Chinese) for trying to promote a K-pop performance by a South Korean group without government approval, according to Nov. 22 report by Yonhap.

The latest showdown will happen on Friday (Dec. 2), when CJ E&M, one of South Korea’s biggest entertainment firms, will host its biggest music festival in Hong Kong. It’s still unclear if the show will air in the mainland.