Russia dispatched two fighter jets to escort four U.S. planes flying over the Black Sea, said Russia's defense ministry.

"Russian fighter crews identified the aerial targets as two U.S. Air Force supersonic strategic B-1B bombers, accompanied by two KC-135 refueling planes, and escorted them over the waters of the Black Sea," the defense ministry said in a statement. 

"After the foreign warplanes had been turned away from Russia's state border, the Russian fighters safely returned to their home airbase," the ministry added.

The statement was released with video footage showing the U.S. military aircraft in flight.

This overlapped with U.S. Secretary of Defense Lloyd Austin's visit to Kyiv, where he believes Russia is blocking peace in eastern Ukraine.

"We again call on Russia to end its occupation of Crimea, to stop perpetuating the war in eastern Ukraine, to end its destabilizing activities in the Black Sea and along Ukraine's borders, and to halt its persistent cyber-attacks," Austin said.

READ MORE 

Beijing to push winter sports to new level

Big stage for miniature art in Paris

Electric vehicles: The complete guide

However, Russia believes Ukraine has been slow to implement the peace deal signed in 2015 that obliges Kyiv to hold hold free elections in the territory and give it special status in the constitution. 

In April, Ukraine's President Volodymyr Zelensky called for a modification of the 2015 Minsk agreement and invited other nations to help mediate the stalled talks.

The incident in the Black Sea follows tensions in the Sea of Japan, where a U.S. destroyer and a Russian warship came within 65 yards of each other over the weekend.

According to the Air Force Magazine, the U.S. supersonic planes, developed during the Cold War era, are currently taking part in NATO exercises across Europe, including over the Arctic, Baltic and Black Seas.