US sanction are bravado, Really? Ask NK, Venezuela and Iran. CN can't behave like that because CN can't hit back. When it is against weaker countries CN behave exactly like that. The QUAD is just beginning. We will see how it evovle.
And what did the sanctions accomplished in China?
They only helped Chinese private sector realise that the US is an unreliable business partner and now everyone and their mother are ripping out US components and where this is not possible they are heavily in R&D to replace them. Come back in 5 years tops and tell me where these mythical US sanctions fundamentally harmed China.
Xi probably opened a champagne to celebrate these tech sanctions. Do you really think that the Chinese gov wasnt aware of their weaknesses?
They tried many times to address some of these but they didn't achieve much and the reason was that the Chinese companies were worshipping western technology and that they drunk the globalisation kool-aid.
And what of the Quad, the qual already started functioning properly last year and it didn't matter anyways, did you see the PLA retreating from the Indian side? Did you see that China got scared and removed their sanctions against Australia. Do you think that China got scared from Japan regarding the islands, I suppose you noticed the new coast guard law which allows the chinese coast gurd ships to fire (aimed at Japan and other SCS claimants)?
And what happened in the first official high-stakes meeting of the Quad? It was basically India milking the rest of the Quad for money to produce vaccines. Did you see anything about military, anything for major diplomatic pact or something else except for empty statements like "Free Into-Pacific trade, rules based order", etc?
IMO the Quad is a tool that India, Australia, Japan will use as a leverage when they individually go to negotiate with China. They dont want to cut economic relations with China so it will mostly remain on the realm of empty and strong statements with no material imlact