Can Trump reach a nuclear deal with Tehran?

US President Donald Trump wants a deal with Iran over its nuclear programme. He has reached out for talks while also tightening sanctions on Iran's economy. For now, Tehran says it will not negotiate under pressure. It was Trump who pulled the U-S out of the previous nuclear deal, saying it did not go far enough. Is there now scope for a diplomatic solution, that is acceptable to both sides? And what will it take to get them to the negotiating table?