Bloomberg reports, citing a statement by the Chinese foreign ministry

China is said to have notified the US of measures against its diplomats in the mainland and in Hong Kong, with the retaliatory move coming in relation to US' own limits on Chinese diplomats at the start of the month here.

Yeah, I'm not sure 'unspecified countermeasures' is what is going to be the straw that breaks the camel's back. Carry on as you will.