US national security adviser Michael Flynn listens to remarks at the National Prayer Breakfast in Washington on Thursday. He had earlier put Iran “on notice” over recent actions by Tehran. Photograph: Win McNamee/Getty Images/EPA

Donald Trump declared on Thursday that his administration had put Iran “on notice”, signalling both a tougher US line with Tehran and a new test of re(...)

 Iranian foreign minister Mohammad Javad Zarif and  US secretary of state John Kerry at the talks between the E3+3 (France, Germany, Britain, China, Russia, USA) and Iran in Vienna, Austria. Photograph: Roland Schlager/EPA

Iran and six powers failed for a second time this year to resolve a 12-year dispute over Tehran’s nuclear ambitions and gave themselves seven more mo(...)