In 1988 China and Vietnam clashed in the Johnson South Reef Skirmish, where?

Question

Minh Mạng, Emperor of Vietnam 1820-1841, was deeply opposed to western involvement in his country and in 1825 outlawed what?

Answer 1

Spratly Islands in the South China Sea
Johnson South Reef is in a high profile and highly disputed area, where ownership of the islands is claimed by six countries, China and Vietnam being two of these.