US President Donald Trump's administration is placing economic sanctions on a major China-based oil refinery and roughly 40 shipping companies and tankers involved in transporting Iranian oil. The move, announced Friday and first reported by The Associated Press, makes good on the Trump administration's threat to impose secondary sanctions on companies and countries that do business with Iran. It's also part of the Republican administration's overall ramped-up campaign to cut off Iran's key source of revenue its oil exports.