A pet shop owner in Yongin, Korea, about 25 miles south of Seoul, set off an international incident recently with an advertising sign featuring . . . a puppy. In the sign, a dog’s head replaces that of Mao Zedong in the portrait hanging at the northern end of Tiananmen Square. Last Tuesday, China’s Foreign Ministry summoned a South Korean diplomat to protest, and the shop’s owner immediately pulled down the sign and apologized to Beijing.

What’s wrong with this picture? First, China’s authoritarian state tried to censor an image appearing in a democracy—and the democracy bowed. Yet there is something even more far-reaching and disturbing in this incident. Since 1954, the People’s Republic has maintained that the Five Principles of Peaceful Coexistence—mutual respect for sovereignty and territorial integrity, mutual non-aggression, non-interference in others’ internal affairs, equality and mutual benefit, and peaceful coexistence—are essential to its foreign policy.

Beijing always says China’s rise will be peaceful, that it does not pose a threat to anyone else, and that it will never interfere in the domestic affairs of another nation. But if its definition of “non-interference” includes the right to ban advertising for a pet shop in a backwater location in another country, then the world is in for a load of trouble.