The aircraft, side number 64-14844 and call sign ELGIN33, took off from the Mildenhall airbase in Britain and flew to the southern part of the Baltic Sea.
According to the report, a Su-27 jet was scrambled to intercept the US plane.
USAF RC-135V 64-14844 c/s ELGIN33 airborne over southern Baltic sea. Prob. intercepted by Flanker. Transponder is on.— Baltic Watch (@BalticWatch) 15 мая 2016 г.
The Sunday flyover is the latest in a series of incidents with the RC-135 aircraft and Russian warplanes in the Baltic Sea in the past few weeks.
Earlier this week, a USAF reconnaissance aircraft also flew over the Baltic Sea, near the Russian border.
The aircraft reportedly conducted a 10-hour observation flight at an altitude of more than 10,000 meters.
Late last month, Pentagon officials claimed that the Russian fighter jet Su-27 allegedly performed a "barrel roll" within about 24 feet of a US Air Force RC-135 reconnaissance plane.
In mid-April, Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said all flights by airplanes from Russia’s Aerospace Forces were completed in accordance with international norms. His comments came in response to statements that Russia completed dangerous actions over the Baltic Sea.