Battery operated listening device mounted inside a One Yuan coin, made in Shenzhen, China with accessories imported from Taiwan. For sale in China, via the internet, for CNY 1400 (USD 215.) Photo credit: pc68.com
In a case from several years ago, a security executive in a Western firm received an allegation that a local employee holding a sensitive position in the company’s Chinese office was a former PRC intelligence officer.
Investigation uncovered a letter of reference from his former employer, an organ of state security, which had been read and filed by local HR staff, but was unknown to management.
The terms in Chinese used to describe agent insertion operations are interesting in themselves, and show parallels to intelligence operations that are standard in other countries:
Da jinqu (打进去) Lit: “Throw inside.” In intelligence and security work, to place a trained person into a target organization.
La chulai (拉出来) Lit: “To draw out.” In intelligence and security work, to recruit an individual already positioned inside a target organization. 
Neixian (内线) “Inner line,” an insertion agent. In common usage this word refers to anyone inside an organization, as opposed to an outsider (see Waixian). This can refer to espionage and police work but can also carry ordinary meanings. The Chinese term may originate from the Russian, as “line” was Soviet jargon for a clandestine network or activity  (e.g.: KGB Line T, the organ focused on acquiring Western high technology). However, the Russian meaning of line (xian) as an organization did not carry over into Chinese practice.
Film poster for Neixian (The Insider), about a CCP clandestine intelligence station (情报站, Qingbao zhan) operating in the closing months of the Chinese Civil War in 1949.
Tewu (特务) Special agent, spy. A tewu is person who participates in a domestic or foreign operation by an enemy espionage organization, has been trained by them and is subordinate to it. A tewu might seek intelligence, build a spy organization or network, commit sabotage, set bombs or fires, wage psychological warfare, or otherwise commit harm. “Tewu are the tools of the imperialists, capitalists, the Kuomintang (Nationalist Chinese) and those who promote reactionary policies.” Though tewu is often used as a derogatory phrase, in 1941 Mao Zedong lauded the importance of his spymaster Li Kenong to the man’s son, saying “Do you know what your father does? He is a major special agent—though one for the Communist Party!” 
Toudi panbian (投敌叛变) Lit: go over to the enemy and turn traitor. Staff of government organs, military personnel, people’s police and militia who defect (投奔, touben) to the counterrevolutionary camp, endangering the interests of the revolution, or who after apprehension by the enemy, sell out their organization and their comrades.  It is possible that employees of a foreign firm asked to cooperate by PRCIC but who report such an approach to their employer could be considered to have turned traitor.
Waixian (外线) Lit: “external line.” In intelligence and police work, often refers to static and mobile surveillance, and field investigations.
Informants and anecdotal evidence indicate the continued placement of trained individuals into foreign businesses in China, as well as penetration by audio and video devices, telephone monitoring, and so on in order to detect potential espionage threats. There is nothing particularly Chinese about such activity, except perhaps for its scale and ubiquity.
Besides the ever-present state, business competitors in China often employ these same techniques to gain commercial advantage. Foreign organizations in China, whether they are businesses, universities, non-government organizations, or others, should keep this reality in mind when planning operations and especially when introducing intellectual property for local use.
An exhaustive list of such terms and other information of concern to security executives and others interested in Chinese intelligence operations will be found in the forthcoming Handbook on Chinese Intelligence, by Peter Mattis and Matt Brazil, which we expect to publish in mid-2018.
 Thanks to Michael Schoenhals for a discussion on these and other points.
 Harvey Klehr, John Earl Haynes, and Fridrikh Firsov, The Secret World of American Communism (New Haven: Yale University Press, 1993), p. 43.
 Wang Zhu (ed), Shiyong Gong’an Xiao Cidian (A Practical Public Security Mini Dictionary), p. 359.
 Li Li, Cong mimi zhanxian zouchu de kaiguo shangjiang huainian jiafu Li Kenong [Li Kenong, the General Who Emerged from the Secret Battlefront at the Founding of the Nation] (Beijing: Renmin Chubanshe, 2008), p. 155
 Wang Zhu (ed), Shiyong Gong’an Xiao Cidian, p. 223.