U.S. President Barack Obama has written to Iran’s Supreme Leader Ayatollah Ali Khamenei, according to a report in The Wall Street Journal, urging the Iranian leader to support progress in the nuclear negotiations and outlining the common interests of the two countries in confronting the forces of the Islamic State of Iraq and Syria (ISIS).

The report comes as the deadline approaches for reaching a deal in the nuclear disputes.

This is the fourth time Barack Obama has written to Ayatollah Khamenei since he took power in 2009.

The news of the letter has not been confirmed by the White House spokesperson, who answered queries by saying the U.S. policy vis-a-vis Iran has not changed.

Reports also indicate that U.S. allies in the region, including Saudi Arabia and Israel, are concerned about the United States coming to terms with Iran, which could be one of the reasons for keeping the letter a secret.