Passenger jets had to dodge Russian bombers flying through air space controlled by Ireland.
The Irish Aviation Authority (IAA) said the two Tu-95 bombers flew some 40 kilometers off the Irish coast on February 18.
As a result, one passenger plane had to change its flight pattern to avoid a potential collision. Another plane delayed its takeoff.
No details were disclosed about the passenger planes.
According to the IAA, the Russian bombers had their transponders turned off, making them invisible to air traffic controllers.
The incident occurred the same day Britain scrambled fighter jets to intercept and escort two Russian military aircraft flying close to the British coastline.
NATO says there has been a dramatic rise in the number of incursions by Russian military aircraft amid mounting tensions between the West and Moscow over the conflict in eastern Ukraine.
Based on reporting by AFP and The Irish Examiner