The US has already blacklisted Chinese tech firms, sought to cut the flow of sophisticated processors and banned its citizens from providing certain help to the country’s chip industry. Washington has also enlisted allies, with Japan saying on Friday that it will expand restrictions on exporting leading-edge chip-making technology, joining similar US-led restrictions by another key supplier, the Netherlands. The move also comes as the US tries to play down the visit this week of Taiwan’s President Tsai Ing-wen, which Beijing has protested. “It’s possible that the investigation of Micron is intended to pressure the US and its allies to...