HONG KONG—China’s arrest of 12 Hong Kong pro-democracy activists, nabbed as they experimented with to flee the town by boat in the encounter of an intensifying crackdown on dissent, is fueling a new war of words and phrases in between Washington and Beijing.

On Sunday, Chinese International Ministry spokeswoman Hua Chunying reported on Twitter that the individuals detained weren’t searching for democratic freedoms but “elements attempting to independent Hong Kong from China.” Other Chinese officers this weekend accused the U.S. of meddling in China’s inside affairs.