I don't know why Trump is engaging in a trade war with China (outside of the pretenses), but I can comment and speculate on some of the subtleties, causes and effects:

• Trump doesn't care about soybeans (at least not very much).
• China doesn't care about cooking oil (at least not very much).
• Trump's earlier statement last weekend looked like "Let's be BFFs" with a smile and a handshake on the surface, but was laden with not-so-subtle threats against China and personal insults against Xi.
• All of Trump's actions, starting from his initial statements of his goals on tariffs several months ago, especially with regards to China, came out like a freight train. When he said them, it was well known that they would cause substantial instability in the market, i.e., there were no surprises about the upheaval, yet they were done anyways, and they were as disruptive as possible.
• China's actions and reactions look like they they want a trade war on a massive scale; like a "WWIII" of trade.
• After investigating the economic beginnings of the previous World Wars, all of their actions on all sides look exactly like what happened previously with the intentional instability in the worldwide economy and Crash. (Notably the Reparations for Germany after WWI, how that came to be, who caused it, how it was resolved, etc. (all steps done and paid for for by Rothschild/Rockefeller) and then the crash of 1929, the Great Depression and the New Deal, which, taken together, created and funded the Nazis and brought about WWII (also all done and paid for by the same group).)
• What if Xi and Trump are allies, and have been for a while, working together towards some purpose, while seeming to be at odds?
• Why does Q reference Red October so often?
• Why is the "Russian Collusion" narrative running at full roar now?
• Why is there every indication that the silver market is about to shut down completely, making silver bullion effectively infinite in value, though I doubt you will be able to sell it at all. (So it will be worth both zero and infinity at the same time).
• Why are pundits (and independent investigators) suggesting that the worldwide debt is unsustainable now?
• Silver is one of the most important commodities in tech (for anything electric, especially anything with a microchip). What happens when all of the computer industry is entirely shut down, even if temporarily?
• Why is 3I/Atlas not acting like it should on about a hundred different levels?
• Why are even the most skeptical "experts" talking about it's atypical behavior and tying it to the possibilities of alien tech?
• What exactly does Q mean when he says: "[SCARE] NECESSARY EVENT"?
• What does Q mean when he says: "Enjoy the Show"?
• How do you force people to change?

You have to first mentally attach the possibility of an intended change. This is a form of predictive programming. Historically, the only way to create a worldwide change of belief is to push propaganda, and using reverse psychology to give people no choice but to adopt a paradigm shift of your own design. People need time to prepare to mentally adopt a specific change antithetical to their previous belief system. Otherwise they will (at least en masse) take on a "deer in headlights" mentally, i.e. the entire world will panic. People have to be prepared to be guided towards a specific outcome.

Why is it all happening now? Because there are several areas and levels to The Programming; AKA the Matrix. If you want to counter such a subversive and pervasive Program, it's best to do it all at once, at Warp Speed; rip the band-aid off. Don't let people fall asleep again (which was the purpose of the 1920s and then the 1950s). Don't allow the cycle to repeat.

End the cycle.