The main reason for the present trade war between US and China is that previous US presidents in the past couple of decades were lenient towards China and their various policies to "force" American/Western companies to transfer the "technology" (usually these are company secrets) in case they wanted to manufacture in China and wanted to access chinese consumer markets. Chinese even started "stealing" the tech secrets of the advanced US semiconductor companies through cyber attacks of western companies' websites and databases, this process just got too much accelerated in the last 10 years or so after 2008 financial crisis in the US after which the US companies became reckless to reduce their production costs by transferring their production lines to China often accepting the "transfer" of technology demand of Chinese government. Then when "Xi jinping" came into power he announced that China will move from being just a cheap labour economy to the one producing "high tech semiconductor technologies" inside china, I think this was announced in 2014 or so, this just raised the "alarm" among the US think tanks that China has accumulated/stolen "enough" high tech "secrets/processes/technologies" that it now is ready to compete the original US high tech companies. That is when "counter China" policy started shaping up in the US, I think even Obama also had "blocked" many Chinese moves of take over of the hightech companies belonging to US or US allies like Britain or sometime even German. I personally know from 2016 news articles when Obama blocked the Chinese attempt of take over of a high tech German company called Aixtron,
https://www.reuters.com/article/us-...ron-bid-after-obama-blocks-deal-idUSKBN13X16H
So the basic work against denying China any kind of western high tech technologies started even before Trump came into power. Trump however has brought the "unbearable trade deficit" that China has progressively achieved against the US in the last decade or so, however the "protection of US/western" high tech technologies by China through coercion of US companies located in China or by hacking attempts to steal the high tech secrets by cyber attacks originating from China still remain one of the most important issues during negotiations between China and US to reach a new trade deal. Also US under Trump is demanding China to "fundamentally" change its economic policies with regards to how it "imposed various conditions of having a chinese partner and tech transfer" for any US or Western companies that show interest in investing in China. So it is a complex issue and China is "no saint" in the this issues as it is made by gullible members on this forum. I have been tracking these economic and "burning trade issues" for years now, so I have a good idea why this "trade war" is happening, china just don't want to be a labour force for foreign companies to make "shoes", "toys", "plastic utensils" etc. anymore, it wants to emerge as a "major player" in hightech semiconductor technologies/products, this is also the reason why "Huawei" is under attack from the US and why China is hell bent to "protect" a "private company" on the paper, but I doubt it is "actually" a private company, it is just a proxy of Chinese state and I think they invested very heavily in this "high tech company" to emerge as a major player in production of high tech products/technologies.