The action taken against prominent local academic Huang Jing should not be seen in isolation or as being directed against any particular country. The China-born American citizen has had his permanent residency cancelled for working with a foreign government to influence Singapore's foreign policy and public opinion here. He and his wife will also be permanently banned from Singapore. This stringent action sends out a stinging reminder that Singapore's foreign policy is Singaporean and not foreign - and hence any interference in it is out of bounds, no matter which foreign quarter it comes from.
The fundamental principle is that no foreigner - and no Singaporean as well - can be allowed to advance the political and diplomatic agenda of a foreign country covertly at Singapore's expense. Espionage - the collection of sensitive national information illegally - is an outright offence. But acting as an agent of influence - to disseminate information intended to change the course of Singapore's foreign policy or its domestic political development - is no less insidious and dangerous.
Of course, every country seeks to influence the behaviour of other nations. However, that effort needs to be carried out through legitimate political and diplomatic channels which are authorised to conduct foreign policy. It cannot fall on individuals, who are present in Singapore in a different capacity, to act as unofficial multipliers of external influence. The integrity of Singapore's decision-making structures would be subverted in no time were such interventions to become habitual.
Indeed, even representatives of friendly countries are not immune from the operation of this sovereign principle. The expulsion of an American diplomat in the late 1980s, for interference in domestic politics, revealed that foreign clandestine operations were not limited to hostile countries but could emanate from even friendly nations. The issue is not the nature of the relationship with particular countries, but the boundaries of probity within which all must conduct their relations with Singapore.
Attempts to test such boundaries are widespread. Australia, for example, is trying to assess the extent to which Chinese agencies are gaining influence over Canberra. There have been explosive allegations of Russian interference in the last American presidential election. There have been reports of America's vast espionage network in China being crippled.
If even large countries can be vulnerable to the covert actions of other powerful nations, it falls on tiny Singapore to ensure that its freedom of manoeuvre is not compromised by the unwelcome attention of foreign players. The Huang Jing episode would serve a useful purpose were it to impress on countries to take Singapore's sovereignty seriously. It does so itself.