Russia–Syria–Iran–Iraq coalition

The Russia–Syria–Iran–Iraq coalition (RSII coalition), also referred to as 4+1 (in which the "plus one" refers to Hezbollah of Lebanon), was a joint intelligence-sharing cooperation between opponents of the Islamic State (IS) with operation rooms in Syria's Damascus and Iraq's Green Zone in Baghdad. It was formed as a consequence of an agreement reached at the end of September 2015 between Russia, Iran, Iraq and the Syrian Arab Republic to "help and cooperate in collecting information about the terrorist Daesh group" (ISIS) with a view to combatting the advances of the group, according to the statement issued by the Iraqi Joint Operations Command.

Source: Wikipedia — Russia–Syria–Iran–Iraq coalition (CC BY-SA 4.0)