South Korean President Park Geun-hye has discovered first hand the feeling of getting the cold shoulder from China.

Under the fluent Mandarin speaker's watch, South Korea had seen improved ties with China, drawn together in part by concern about Japan's wartime past and the military ambitions of Prime Minister Shinzo Abe. Park was the only leader of a U.S. ally to attend a military parade in China last year for the 70th anniversary of the end of World War II.

Now, relations that were hailed by both countries as the best in history have soured, and Park may get a frosty reception in China next month for the Group of 20 summit. The reason: Her agreement to deploy a U.S. missile shield on Korean soil.