Since its creation over 20 years ago, U.S. Open Skies policy has spread throughout Europe and Asia. As the United States has reached Open Skies agreements (OSAs) with over 114 nations from around the world, it can be said that the greater part of global aviation market has liberalized today.

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Because of such this widespread liberalization, international carriers have expanded both their markets and flight frequency, meaning lower fares. Moreover, alliance formation has led to closer cooperation among carriers, and their strategic global network planning is progressing.

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On the other hand, due to stronger cooperation among the carriers, issues with OSAs have increasingly emerged, such as oligopolies in some markets and intensification of competition among traditional alliances – in part thanks to newcomers outside of the alliances.