USA officials have accused the Russian pilot of acting in an "unsafe" manner by crossing in front of the Navy P-8.
On Saturday, a U.S. Navy P-8A Poseidon was flying in worldwide airspace over the Black Sea when it was intercepted by a Russian SU-30, Eucom spokeswoman Meghan Henderson said.
In June, a Russian SU-27 fighter jet flew within five feet of a U.S. Air Force RC-15 reconnaissance aircraft over the Baltic Sea.
In June, the pilot of a USA bomber filmed the nail-biting moment a Russian fighter jet swooped alongside him over the Baltic Sea.
"The US aircraft was operating in global airspace and did nothing to provoke this Russian behavior".
The U.S. P-8A Poseidon did nothing to provoke the maneuver defense spokesperson Michelle Baldanza said
The Russian fighter "spoiled the plans of the American reconnaissance jet", Russian state TV channel Rossiya 24 reported, while state-run Sputnik radio cited a professor at Russia's military studies academy concluding that Russia's "military aviation just doesn't fly that way".
The U.S. plane "was operating in worldwide airspace and did nothing to provoke this Russian behavior", a Pentagon spokeswoman was quoted by CNN as saying.
As for the unsafe aspects of the Su-30s actions, Baldanza said that its close approach and use of afterburners forced the Poseidon aircraft to enter its "jet wash".
As a result of the "provocative" manoeuvre, the U.S. aircraft did "a 15-degree roll" that could have caused "serious harm and injury to all air crews involved", a USA official said.