Comments by the Chinese foreign ministry
This comes on the back of the US announcing that it will pare back its special status treatment of Hong Kong, saying that they will take back some trade benefits it affords Hong Kong; adding that further measures are also being evaluated.
US secretary of state, Mike Pompeo, also tweeted out this:
"Today, the United States is ending exports of @StateDeptPM controlled U.S. origin defense equipment and sensitive @CommerceGov controlled dual-use technologies to Hong Kong. If Beijing now treats Hong Kong as "One Country, One System," so must we."
As for China's "retaliatory measures", this is still all part of the act with the two sides continuing to put up a show on the matter. I wouldn't expect any major chaos to ensue.
If either side was serious about escalating things, it would've been done the minute China introduced the national security law at its parliament last month.