The US's official response, as posted on the US consulate in HK:
https://hk.usconsulate.gov/n-2020063001/
The United States will not stand idly by while China swallows Hong Kong into its authoritarian maw. Last week, we imposed visa restrictions on CCP officials responsible for undermining Hong Kong’s autonomy. We are ending defense and dual-use technology exports to the territory. Per President Trump’s instruction, we will eliminate policy exemptions that give Hong Kong different and special treatment, with few exceptions...
Empty political bluffing or is there real teeth to this statement? We'll see. No doubt China will retaliate. And so the tit-for-tat will go on and get worse.