The franchise has explored the idea in the past with 'Modern Warfare 3', which featured 'Open World Missions', but it's thought the new feature has been "built from the ground up".
As reported by Insider Gamer, the new Gulf War campaign will task the player and their with navigating a map closer to 'Far Cry' than a typical 'Call of Duty' world.
As well as a fast travel system, players will get to use vehicles to move from one area to the next.
There is currently no word on how many linear missions there will be, but sources added that some "will be integrated into the game".
The campaign is being worked on by Raven Software, with multiplayer and zombie modes being developed by Treyarch Games.
Meanwhile, sources also told the outlet that the 'Call of Duty' franchise could embrace more open-world campaigns rather than linear stories.
It's believed that 'Call of Duty 2025' - which has been given the codename Saturn and is yet to have an assigned leading developed - may also have a similarly open campaign.
The game itself is still early into its development, with around 20 months left until launch.
However, the sources suggested the shift from a linear campaign to open world is based on the idea of streamlining development rather than any other issues.