The IAA referred to in the game is a government intelligence agency that assigns missions to players.
What happens when you complete ALL the IAA missions?? | GTA online
Grand Theft Auto is one of the most popular games ever to hit the gaming world, and with the new missions and storylines introduced in the online version, it only gets better at showcasing all that awesomeness.
The International Affairs Agency, or IAA as they are called in-game, is a government intelligence agency that at the time of GTA Online gave players missions like the Doomsday Heist to play through in 2017. The last event or Mission was for players to assume the identity of a newly recruited IAA -agent to take down a criminal conspiracy in southern San Andreas.
After a player completes all 6 IAA missions, they are directed to go to a bunker/silo in the final mission to find some fuses, turn on the bunker, connect to some servers, and kill all the juggernauts in the bunker and escape the guards. A helicopter containing Hertz's former henchmen will fly in an attempt to put an end to the matter after players have successfully exited the silo.
