The Wall Street Journal reports that Iran’s Supreme Leader has sent a letter to Barack Obama, adding that Ayatollah Khamenei used his secret contacts to forward the letter to the U.S. president.

The Wall Street Journal quotes an unidentified Iranian diplomat saying the letter was written in recent weeks and is a response to the letter Obama sent to the Iranian leader last October.

The letter, according to the report, contains statements regarding the possibility of cooperation between Iran and the U.S. in the fight against Daesh (ISIS) after an agreement is reached in the nuclear negotiations.

The report indicates that the letter is “respectful” but contains no commitments or promises.

Receipt of the letter has not been confirmed by the White House, according to The Wall Street Journal; however, Iranian officials have said in recent months that some of Barack Obama’s letters have gotten a response, although it was not indicated precisely who responded.