The Chinese government has made it clear they aren't exactly fans of all new technology. Last month, they went after iPhone's for being a national security risk, and authorities were recently spotted touring Microsoft offices, and not to learn about Excel. Today, the government announced they will restrict use of instant messaging services.
South Korean officials says there informed that "foreign services" were blocked because they could be "used to exchange terrorism-related information." South Korea was told the "foreign services" targeted were Kakao Talk and Line, two instant mobile messaging platforms that will now be blocked in China.
The Chinese government claimed they "confirmed" terrorism related messages were passed using the platforms, however, this seems unlikely, as they are both fully private messaging applications. Chinese officials did not offer any details as to what the messages were, or how they may have intercepted them.
This comes as part of the government's worry about social media. Even though it is still highly controlled, social media allows both journalists and Chinese citizens to pass non-state controlled news quickly. The government is seeking to curtail that, noting that only "established" (read: state-controlled) media could circulate political and social news.