A top UN official urges world powers and Iran to urgently work to restore the 2015 nuclear deal, warning that its success or failure matters to all. The US has stated that a nuclear Iran can never be an option and is prepared to use all elements of national power to prevent it. European and Iranian diplomats have met to discuss defusing tensions before Trump's return to the White House. Britain, France, and Germany are ready to trigger a 'snap back' of all international sanctions on Iran to prevent it from acquiring a nuclear weapon. Iran denies pursuing nuclear weapons and says its program is peaceful.