The Reiko Accords are a non-aggression pact between Earthrealm and Outworld.
The accords are named after the Outworld general Reiko, and were created after he and the cleric of chaos Havik were stopped from achieving their plans of sowing chaos throughout the realms. Afterwards, the protector god of Earthrealm, Raiden, Special Forces colonel Sonya Blade, and emperor of Outworld Kotal Kahn, agreed to a pact that would call for discussion before conflict between their realms and leave any collaboration at their mutual discretion.
The pact remained in effect for many years. However, once Kotal Kahn gained possession of the Amulet of Shinnok from Mileena, he chose to ignore the accords and claim it for himself, believing Earthrealm unfit to guard it. The current state of the accords is unknown and what the ramifications of Kotal Kahn's blatant disregard for them and his subsequent invasion of Earthrealm remain unknown.