No one is going to war with China... China is slowly disowning NK over it because they know it...
Multi-sourcing is stupendously expensive so people won't do it. There is no economic sense in not going for the cheapest source if the probable return is good enough, which it more than is.
Don't ever say there won't be war. The nuclear clock is now 2 minutes to midnight, thanks mainly to the rogue nuclear nations of China, USA, Russia and North Korea.
The Sumitomo electronics plastics plant fire was a single source (almost) for electronics component plastics. It burned down in the late 90's, causing global chaos (esp. DRAM chips). More than one source means competition, too. Competition is healthy, as has been demonstrated time and time again. And the cheapest source is not necessarily good - cheapest could mean slavery, no work safety, oppression of workers, environmental vandalism and crap quality.
We should be supporting our local vendors and in particular our local manufacturers wherever possible, else you may just be part of the problem. Not just for electronics either. Pay a little more, get much better quality and service. A big tax hike on imports will help our local manufacturers.