President Obama reportedly wrote "secret letter" to leader of Iran President Barack Obama and Iran's Supreme Leader Ayatollah Ali Khamenei have a shared interest in fighting the jihadist group Islamic State. That is apparently the view of the US president which he aired in what has been described as a "secret letter" to Iran's leader. The letter reported by the Wall Street Journal is seen to underline the president's view that Iran is important in an emerging campaign against ISIL. It's understood to be at least the fourth time he has written to the Iranian leader. The latest correspondence also urges Ayatollah Ali Khamenei toward a nuclear agreement. "There is a long tradition of mistrust between the two countries, whether they can manage to say "yes" to what clearly would be better for Iran, better for the region, and better for the world, is an open question. We'll find out over the next several weeks," President Obama told reporters. Negotiations on the nuclear issue are set to start this weekend when US Secretary of State John Kerry is scheduled to meet his Iranian counterpart Javad Zarif in Oman. According to the Wall Street Journal, Washington officials have placed the chances of a deal at only 50-50.