People have been going on about China in the US since their ascension to the WTO. Plenty of federal politicians have been elected on platforms for pushing hawkwish trade policy with China.
I think that's a bit of a selective history though. In the 1990s there were plenty of politicians that fervently supported it, though the reasons they supported probably had something to do with this[1].
The parent comment implied that the US has done a very sudden turnaround of belief; that's a selective reading of history.
The US has always had undertones of economic nationalism, particularly around jobs getting outsourced to China. It just took a while for the pot to boil over.
