https://www.thedrive.com/the-war-zone/27206/the-russians-just-did-a-fly-by-of-area-51

........      The Russians are operating their Tu-154M aircraft configured for surveillance flights sanctioned under the Open Skies Treaty that allows member countries to conduct surveillance flights over each other's territory relatively unimpeded. The aircraft are equipped with imaging equipment with specific limitations and monitors from the country being surveilled are onboard the flights to make certain the party complies with the parameters of the treaty. This latest series of Russian Open Skies flights are being conducted out of Great Falls, Montana and are covering a slew of strategic points in the western part of the United States, including the highly secure Nellis Test and Training Range (NTTR) in southern Nevada, home of Area 51.

The Russians Just Did A Fly-By Of Area 51 ...