WASHINGTON—President Barack Obama secretly wrote to Iran’s Supreme Leader Ayatollah Ali Khamenei in the middle of last month and described a shared interest in fighting Islamic State militants in Iraq and Syria, according to people briefed on the correspondence.
The letter appeared aimed both at buttressing the campaign against Islamic State and nudging Iran’s religious leader closer to a nuclear deal.
Mr. Obama stressed to Mr. Khamenei that any cooperation on Islamic State was largely contingent on Iran reaching a comprehensive agreement with global powers on the future of Tehran’s nuclear program by a Nov. 24 diplomatic deadline, the same people say.
The October letter marked at least the fourth time Mr. Obama has written Iran’s most powerful political and religious leader since taking office in 2009 and pledging to engage with Tehran’s Islamist government.
The correspondence underscores that Mr. Obama views Iran as important—whether in a potentially constructive or negative role—to his emerging military and diplomatic campaign to push Islamic State from the territories it has gained over the past six months.
Mr. Obama’s letter also sought to assuage Iran’s concerns about the future of its close ally, President Bashar al-Assad of Syria, according to another person briefed on the letter. It states that the U.S.’s military operations inside Syria aren’t targeted at Mr. Assad or his security forces.
Mr. Obama and senior administration officials in recent days have placed the chances for a deal with Iran at only 50-50. U.S. Secretary of State John Kerry is set to begin intensive direct negotiations on the nuclear issue with his Iranian counterpart, Javad Zarif, on Sunday in the Persian Gulf country of Oman.
“There’s a sizable portion of the political elite that cut their teeth on anti-Americanism,” Mr. Obama said at a White House news conference on Wednesday about Iran’s leadership, without commenting on his personal overture. “Whether they can manage to say ‘Yes’…is an open question.”