Two Russian warplanes "dangerously" intercepted an unarmed RAF spy plane over the Black Sea last month, the Ministry of Defence has said on Wednesday.
A Russian Su-35 fighter approached the surveillance aircraft - close enough to trigger its emergency systems - while a Su-27 jet carried out six passes in front of it.
The MoD said the Rivet Joint had been conducting a routine international flight to aid in securing Nato's eastern flank.
BBC Security Correspondent Frank Gardner described the incident as "really serious", pointing to the potential for escalation amid tensions between Russia and Nato.
