The United States forbids diplomats from China from having sex with Chinese citizens. What is the reason

The US government has banned American government officials in China, as well as their families and security-authorized contractors, from engaging in any romantic or sexual relationships with Chinese citizens, according to AP .
Four individuals with direct knowledge of the matter told the Associated Press (AP) that the new policy was implemented in January by American ambassador Nicholas Burns, just before leaving China. They spoke on the condition of anonymity, given the confidential nature of the directive.
While some US agencies already had strict rules regarding such relationships, a general”no-fraternization” ban had not been publicly announced since the Cold War. It is common for American diplomats in other countries to have relationships and even marry locals.A more limited version of this policy was introduced last summer, prohibiting American personnel from engaging in romantic or sexual relationships with Chinese citizens who worked as security agents or support staff at the US Embassy and the five consulates in China. However, in January, Burns expanded the ban to cover all such relationships with Chinese citizens in China, just days before Donald Trump took office as President. AP has not been able to determine exactly how the policy defines “romantic or sexual relationship”.
Two of the sources said that the policy was first discussed last summer, after members of the US Congress contacted Burns to express their concerns that the restrictions on such relationships were not strict enough. The Select Committee on the Communist Party of China did not respond to requests for comment.
Details, HERE.