President Donald Trump and his aides were confronting dramatically increased tensions with Iran on Thursday after the downing of a US drone near the Persian Gulf. "Iran made a very big mistake!" the President tweeted mid-morning as he and his national security officials huddled to weigh possible responses. The ominous — if vague — message came after Iran's Revolutionary Guard said it had shot down an "intruding American spy drone" after it entered into the country's territory Thursday.