Taking to social media, Trump called China a "hostile trading nation" and said its electronics were still subject to the lower 20 percent tariff rate imposed in March over the continued export to North America of chemical precursors used in the production of the opioid fentanyl.

But shares in TSMC, the world's largest contract chipmaker have slipped, after US President Donald Trump said he would announce a tariff rate on imported semiconductors over the next week. He did add however, that there would be flexibility on some companies in the sector.