President Donald Trump demands that iPhones sold in the U.S. must be manufactured in the country to avoid a 25% tariff.Apple's shares dropped over 2% in premarket trading following Trump's statement.Moving iPhone production to the U.S. could increase the phone's price by at least 25%, with estimates putting the cost of a U.S. iPhone at $3,500.Trump has criticized Apple and called for increased domestic manufacturing, while also proposing a 50% tariff on products from the European Union.