Russian defence ministry said it dispatched Su-27 jets to check out the US P-8 Poseidon planes.
Russian fighter jets on Wednesday intercepted US military spy planes over the Black Sea "in strict accordance with international rules" as they tried to snoop on Russian army exercises, Moscow said.
The defence ministry said in a statement it dispatched Su-27 jets to check out the US P-8 Poseidon planes as they "twice tried to get close to the Russian border over the Black Sea without their transponders turned on".
"After the Russian fighters got close to the spy planes for visual confirmation and to determine their wing numbers the American aircraft changed course sharply and flew away," the statement said.
"The Russia pilots acted in strict accordance with international rules for flights."
A US defence official said a Russian plane flew within 10 feet (3 metres) of a US spy plane in a move "considered unsafe and unprofessional".
The Russian statement said that this was "not the first attempt" by NATO aircraft to get close to the country's borders to spy on major military drills currently taking place on the Ukraine border and the annexed Crimea peninsula.
Relations between Russia and the West are currently at their lowest point since the Cold War over Moscow's seizure of Crimea from Ukraine and alleged fuelling of a separatist conflict in the ex-Soviet country.
The two sides have reported an uptick in similar mid-air incidents between their forces as Moscow flexes its muscles and US-led alliance NATO beefs up its forces in Eastern Europe.