Earlier quoted context omitted.
There are two things China has been doing for years that the WTO hasn't put an end to. The stated goals of the trade war include stopping those, which I can - as anything but a fan of anything to do with Trump - actually agree need to stop. I'm far from certain the scale and breadth of tariffs involved are necessary to stop them, but I agree those two practices need to stop. One of those is outright IP theft. One esp…
One of the things he campaigned on in 2016 was bringing manufacturing jobs back to the US for low-skilled workers. I can see that being a third thing this could possibly help.
Countries don't only impose import tariffs when trade wars get really ugly, either. Imagine all of OPEC hitting the US with export tariffs in their countries. Or imagine Mexico, Germany, Japan, and South Korea charging export tariffs on their car manufacturing for exports to the US. A 10% or 20% export tariff costs the consumer the same as an import tariff of the same amount, but the money goes to the exporting country's government, which if they want they can use to subsidize the industry being taxed. The target country can't credibly accuse you of dumping if you're intentionally charging them more than everyone else.
The US does a lot of outsourcing of parts and subassemblies. Then US companies import those to make into other products or assemble them into more complex systems. Those import costs go up under tariffs, and much of the demand goes down for the finished product when there are tit-for-tat tariffs to sell those overseas. Meanwhile if some country neither party is in a trade war with starts buying the parts and doing the final assembly, they can undercut US manufacturers' prices because they have lower taxes in place on those products.
It would take years to move all the vertical supply chains into the US and to do so would be extremely expensive. The low-cost labor from overseas would likely be replaced with factories with a much higher level of automation to keep the costs down. That's going to provide more professional jobs and highly skilled technical jobs and fewer low-skilled and trades jobs than people might like to imagine. All the while, the resources to build those new factories is higher from the tariffs unless we're building it all with domestic parts. There is no training program in place of which I'm aware to teach coal miners and steel mill workers to assemble things like motherboards and flat panel displays, either, which means the labor costs for those things is much higher than just the wages if those jobs aren't automated away.