Mousavi threatening to spill Iran's secrets?

Mir-Hossein Mousavi, leader of Iran's opposition, is threatening to reveal secrets that he became aware of during his stint as Iran's last prime minister from 1981 to 1989, says a new report in Al Arabiya.

According to the article, Mousavi wrote a letter of resignation in 1988 which was rejected by the late Ayatollah Khomeini and president Ali Khamanei. This letter, which he is threatening to make public, discloses some foreign Iranian adventures in Lebanon, Saudi Arabia and Iraq. These reportedly include sniper attacks in Lebanon, airplane hijackings and bomb plots against pilgrims going to Mecca.

Ali, who sent me the link, says that this letter shows the level of division in the Iranian government at the time, and notes it is probably worse now. However, Mousavi himself was PM under Khomeini, so how much he should be trusted himself is not so clear.