In 1988 a classified Vietnamese Ministry of Public Securityâs in-house professional journal published this article offering ideas on how to utilize the âpsychological characteristicsâ of the ethnic Chinese in the interrogation of suspected âChinese spiesâ. At the time the article was published, the once-close alliance between the Vietnamese and Chinese Communist Parties, which Mao Zedong described in 1967 as being âas close as between lips and teethâ, had deteriorated into a vicious military and political conflict between the two former allies. Chinese efforts to collect intelligence on and to foment internal opposition against the leadership of the Vietnamese Communist Party were of special concern to Vietnamâs security service, and ethnic Chinese residents of Vietnam naturally became a primary focus of Vietnamâs counter-espionage efforts.