Moscow: A US defence attache has been summoned by Russia's Defence Ministry after an incident over the Sea of Japan near Russia's eastern borders, where an American spy plane was detected flying too close to civilian aircraft.

Russia's air defence detected an RC-135 spy plane belonging to US Air Force on Sunday, the ministry said in its statement, according to RT online, the plane was on an air reconnaissance mission with all of its transponders having been shut off, it added.