Russia detected a US reconnaissance drone RQ-4 Global Hawk above the Black Sea. The drone was flying at a high altitude towards the Russian border.
US UAVs conduct such flights on a regular basis. The US Air Force has 42 aerial vehicles of the type.
In the autumn of 2016, reconnaissance aircraft P-8 Poseidon of the US Navy with their transponders off tried to approach the state border of the Russian Federation over the Black Sea twice.
Pravda.Ru
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