【明報專訊】BEIJING has announced sanctions on eleven US politicians and heads of US organisations as countermeasures against Washington's sanctions on eleven officials of the Chinese central government and the HKSAR government. It is the first time that the two countries have imposed sanctions against each other over Hong Kong affairs. The development is of tremendous political symbolic significance and marks the formal beginning of the two countries' diplomatic war in Hong Kong, despite the limited number of people involved. Hong Kong has seen significant structural changes in its internal and external situations ever since the outbreak of the anti-extradition storm. Beijing's enactment of the National Security Law in Hong Kong to crack down on collusion with foreign forces is meant to aim for both internal and external targets. The more Washington plays the "Hong Kong card", the harder Beijing's countermeasures will certainly be. Unilateral sanctions are a kind of highly hostile diplomatic act that is by no means authorised by the Charter of the United Nations. Now that Washington has fired the opening salvo by imposing unilateral sanctions over Hong Kong, there could be even more political storms in the coming days.