Where did the Iraqi Air Force flee to safe haven in the Gulf War?
Aside from which, they have certain common interests.
Both have a "Kurd problem".
They share an enemy: Us.
While the two regimes mix like oil and water, and despite the Iran-Iraq Mutual Decade Long Memorial Bloodbath, there is some history of cooperation.
It could be Baghdad and Teheran...
Well, add to that the practical problem.
They do not understand one anothers' language.