He’s been talking about it for months, but looks like he’s going to actually introduce it. An embedded-emissions tariff like this was proposed during early draft outlines of Build Back Better, but didn’t survive negotiation.
I’ll note that his idea of ‘more methane gas instead of coal’ is something which might have been a reasonable intermediate step 30 years ago. It’s not now, in a world where wind and solar are the cheap option.
We know from our experiences with Trump’s idiocy that China definitely WOULD retaliate with tariffs of their own, to the detriment of everyone except the demagogues getting votes out of it but ESPECIALLY the working class of both countries.