A Russian fighter jet flew within several feet of a US reconnaissance plane in what the US said was an unsafe manoeuvre over the Baltic Sea.
Navy Captain Danny Hernandez said the Russian pilot was flying at a high speed and had poor control of the aircraft.
Capt Hernandez, a US European Command spokesman, said the close encounter was unprovoked by the US aircraft.
He said it is not clear if there was any communication between the aircraft.
It is not known how many US crew were on the plane.
Capt Hernandez said the incident was on Monday when the US RC-135 was on a routine mission in international airspace.
Intercepts between US and Russian aircraft are common and are generally not as dangerously close.