United States President Donald Trump has threatened to impose tariffs of up to 300 percent on semiconductor imports, with exemptions for foreign companies that commit to manufacturing in the US.Trump has cast the proposed tariff as a way to drive investment to the US, but experts say it could also disrupt global supply chains and even penalise companies already making chips in the US.What are the details of Trump’s plan?Few details have been released since Trump announced plans for a 100 percent tariff at a White House event on August 7.The US president said exemptions would be given to companies that build research or manufacturing facilities in the US, but tariffs could be applied retroactively if they failed to follow through on their planned investments.“If, for some reason, you say you’re building, and you don’t build, then we go back, and we add it up, it accumulates, and we charge you at a later date, you have to pay, and that’s a guarantee,” Trump told reporters.On Friday, Trump told reporters on board Air Force One that more details would be announced soon and that the tariff could be much higher than previously suggested.“I’ll be setting tariffs next week and the week after, on steel and on, I would say chips – chips a …