A Royal Air Force Boeing RC-135W aircraft operating over the Black Sea on Wednesday played cat and mouse with Russian forces for almost four hours as it probed Russian-occupied Crimean Peninsula air defenses. [...] Two RAF Typhoon Eurofighters launched from Mihail Kogălniceanu airport, a NATO air base near the Romanian port city of Constanta, tailed the Rivet Joint, flying escort patterns ranging close-in, at 50 kilometers (31 miles) distance, flight data showed.

Typically, the surveillance aircraft has a 20–25-person flight crew and equipment technicians. The last time NATO mounted a deep penetration manned flight towards Crimea, was on June 28, when an RAF RC-135 operated some 200 kilometers from the occupied peninsula.

At the same time as the Rivet Joint headed out from the Romanian coast, the usually little-used airspace was being used by a US Navy Poseidon maritime patrol plane, three Romanian civil air helicopters flying search and rescue patterns, and a civil Airbus 321 airliner flying, a little strangely, in tight circles with no apparent clear destination.