US President Donald Trump has condemned Iran as a "fanatical regime" and refused to continue signing off on a landmark international nuclear deal.In a combative speech on Friday, Mr Trump accused Iran of sponsoring terrorism and proposed new sanctions.He said Iran had already violated the 2015 deal, which imposed curbs on Iran's nuclear capability in return for easing international embargoes.International observers say Iran has been in full compliance with the deal.Speaking at the White House, Mr Trump said he was acting in order to deny Iran "all paths to a nuclear weapon"."We will not continue down a path whose predictable conclusion is more violence, more terror, and the very real threat of Iran's nuclear breakout," he said.