US President Donald Trump signalled on Sunday he is prepared to let economic pressure mount against Iran, apparently backing away from ordering more military strikes even as Tehran issues tough demands. "We are low-keying it," Trump said, according to the news outlet Axios, which said it spoke to him in a brief phone call. Only a week ago Trump made the latest of his series of threats to hit Iran hard, only to back off, as he presses for a deal to end the war he started along with Israel on February 28.