The office of the commissioner for foreign affairs in Hong Kong once played its consular role in the shadow of the ministry in Beijing, occasionally taking charge of sensitive issues such as American warship visits to Hong Kong and air-rights negotiations, or intervening in the Manila hostage crisis. But since Occupy Central it has taken an increasingly high profile in the city’s political affairs, thanks to a series of events that have reshaped the environment under “one country, two systems”, such as the 2019 anti-government protests, the US-China trade war , rising tensions across the Taiwan Strait, a new national security law and US sanctions on local officials. The office has made it clear that this city’s affairs are China’s internal affairs. Hong Kong is seen as a new battleground between China and the US, a key factor in the commissioner’s office assuming a higher profile. The latest appointment to the post is a case in point. It reflects Beijing’s concern about external interference in Hong Kong. Liu Guangyuan is a veteran diplomat seasoned both in US-China relations and security issues. China’s diplomats have become more assertive globally in their country’s interests. Until recently Beijing’s ambassador to Poland, Liu was such an example, notably over moves to exclude Huawei from development of 5G networks. He is well-credentialed for the role of the foreign ministry’s man in Hong Kong, where one of the office’s powers is now to vet contacts between foreign diplomats and local politicians and officials. His appointment is not the only evidence that Hong Kong as on the front line of China-US rivalry. It follows that of a deputy, Pan Yundong, one of the foreign ministry’s top advisers on Taiwan. Foreign affairs remain the preserve of Beijing. But the two postings, one an experienced diplomat who is a former head of external security for the ministry, and the other a specialist on Taiwan, underlines the city’s unique role at a time of global uncertainty. They are diplomats for the times in Hong Kong. Whereas the city was once a go-between for cross-strait relations, the Taiwan issue is now complicated by Washington’s forging of closer ties with Taipei and provocative naval movements. Moreover, Taiwan has been accused of fanning the flames of protests in 2019. Pan belongs to the first generation of China’s Taiwan experts. His deep experience includes terms as deputy chief of the foreign ministry’s Department of Hong Kong, Macau, and Taiwan Affairs. Hong Kong’s status in China’s diplomatic affairs under one country, two systems is now not only unique and delicate, but also much more complex. The commissioner’s office will need all the experience of its top officials to deal with demanding challenges while safeguarding the concept of one country, two systems.