Black Sea area have been spotted with a Russian fighter jet making multiple close-range bypass near an American navy destroyer, according to The Pentagon. The American warship was reportedly designated in that area of the Black Sea because the Russian military allegedly monitored NATO's systematic build-up of naval forces in the region.

According to the US military, the Russian fighter flying over the Black Sea was seen unarmed, and thus called the passing over the Black Sea "provocative and unprofessional".

Pentagon spokesman Colonel Steve Warren said of the Russian fighter flying over the Black Sea where an American navy destroyer was positioned, "This provocative and unprofessional Russian action is inconsistent with their national protocols and previous agreements on the professional interaction between our militaries."

Reuters reported that according to the Pentagon, the jet passing over the Black Sea was a Russian Su-24 aircraft, or Fencer. It allegedly made 12 passes at low altitude near the USS Donald Cook, which at the time was making a patrol in international waters in the western Black Sea.

Recently, the Associated Press was told by a military official on April, 12 that a Russian aircraft also flew repeatedly within 1,000 yards of the USS Donald Cook at about 500 feet above sea level for over 90 minutes. The official detailed that the destroyer's crew made several attempts to radio the Russian warplane requesting it state its reasons as to the manoeuvre and to issue warnings. However, the Russian aircraft's pilot made no response to the destroyer's calls.

According to the Pentagon, the Russian fighter jet then was not armed with any aerial bombs, as with the Russian fighter which passed over the Black Sea now.

Black Sea area on April 10 was based upon by the USS Donald Cook, a destroyer equipped with the powerful Aegis missile defense system. According to the US Defense Department, the ship's mission was "to reassure NATO allies and Black Sea partners" following the events in Ukraine. It entered waters of Romania Monday.