"We will make a decision based on our national interests. In any case, we can say that this will be yet another blow to the European security", Grushko said, when asked what Russia would do if the United States left.
At the same time, he remarked that the US had not notified Russia about its decision to leave yet.
The Open Skies Treaty was signed in Helsinki on March 24, 1992. Currently, it comprises 34 member states. Russia ratified the treaty in May 2001. The parties to the treaty may conduct unmanned surveillance flights over each other's territories in order to gather information about military activities of concern.