So it's suposition. For most companies IP is the most important advantage, they certainly would have more success finding a cheap place that respects IPs than to have every company in the world able to copy them.
The funny thing about every single economist (besides being able to find at least one that wouldn't agree) is also that we had "every single jornalist" saying how Trump would doom america and cause 3rd WW, etc. Didn't happen.
You should ask yourself why American companies have chosen China for production and stuck with them for so long despite the risk of getting their knowledge copied. It's because low production costs are more important to them than anything else, so naturally they are against tariffs because that undermines their entire system of producing cheap in China and being able to have good prices in the USA. If tariffs were introduced, they would have to rise the prices of their products to make customers pay for the difference, because they wouldn't eat the costs themselves.
As for World War III, there were more talks about Hillary Clinton being able to cause it, because she was outspoken against Russia whereas Trump wanted to be BFF with Putin.