By Idrees Ali

WASHINGTON (Reuters) - A Russian warship carried out "unprofessional" maritime operations in close proximity to a U.S. Navy ship in the eastern Mediterranean Sea, a U.S. Defense official said on Friday.

This is the second time the same Russian vessel has come within close proximity of a U.S. Navy ship this month. On June 17, the Yaroslav Mudryy came within 315 yards (288 meters) of the USS Gravely, an incident U.S. officials called "unsafe and unprofessional," but which the Russian Defense Ministry disputed.

Recent months have seen a number of similar Cold War-style incidents at sea and in the air, with each country's military accusing the other of dangerous approaches in international waters and airspace.

The U.S. Defense official, who was speaking on the condition of anonymity, said the most recent incident took place on June 30 when the Yaroslav Mudryy came unnecessarily close to the USS San Jacinto and maneuvered in it's wake.

"The closing distance by Yaroslav Mudryy before the ship turned away from San Jacinto is considered a high risk maneuver, highly unprofessional, and contrary to international maritime regulations," the official said.

The official added however, that the U.S. guided-missile cruiser was never threatened by the maneuvers.

"Conducting aggressive, erratic maneuvers and moving unnecessarily close to another ship in open ocean is inconsistent with prudent seamanship," the official said.

At the time of the incident, the San Jacinto was carrying out operations against Islamic State militants in Iraq and Syria with the USS Dwight D. Eisenhower, the official said.

In another incident in April, the U.S. military said Russian SU-24 bombers had simulated attack passes near the USS Donald Cook in the Baltic Sea, with one official describing them as one of the most aggressive interactions in recent memory.

U.S. Secretary of State John Kerry said at the time that the behavior of the Russian pilots was provocative and dangerous, adding that "under the rules of engagement that could have been a shoot-down".

(Reporting by Idrees Ali; Editing by Andrew Hay)