The 1992 treaty allows the 34 member countries to conduct short notice, unarmed, reconnaissance flights over the other countries to collect data on their military forces and activities.
The Trump administration has cited Russian restrictions on Open Skies flights as the reason why it sought to exit the treaty, accusing Moscow of imposing limits on flights near its exclave of Kaliningrad, an area between Poland and Lithuania where the Russian military maintains a robust presence.
The US has also accused Russia of denying flights within 6.2 miles of the Georgia-Russia border, and denying a previously approved flight over a major Russian military exercise.
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