A Russian warship carried out aggressive and erratic manoeuvres close to a US Navy ship in the eastern Mediterranean Sea, the second such Cold War-style incident there in a matter of weeks, the US military says.
The US European Command on Saturday said the Russian frigate, Yaroslav Mudry, came unnecessarily close to the guided-missile cruiser USS San Jacinto on June 30 and manoeuvred in its wake.
In a statement, EUCOM said the US ship had not been threatened and it maintained course and speed.
"But the closing distance by Yaroslav Mudry before the ship turned away from San Jacinto is considered a high risk manoeuvre, highly unprofessional, and contrary to international maritime regulations."
Referring to the Yaroslav Mudry's close "aggressive, erratic manoeuvres", EUCOM SAID: "These actions can unnecessarily escalate tensions between countries, and could result in dangerous miscalculations or accidents."
There have been several similar incidents - reminiscent of Cold War confrontations between the rival superpowers - at sea and in the air in recent months, with the US and Russian militaries accusing each other of dangerous approaches in international waters and airspace.
US officials said earlier this month that on June 17, the Yaroslav Mudry came within 288 metres of the USS Gravely.
They termed that incident "unsafe and unprofessional". The Russian Defence Ministry disputed this.
At the time of the incident, the San Jacinto was carrying out operations against Islamic State militants in Iraq and Syria with the aircraft carrier USS Dwight D Eisenhower.
In another incident in April, the US military said Russian SU-24 bombers had simulated attack passes near the USS Donald Cook in the Baltic Sea.
US Secretary of State John Kerry said at the time that the behaviour of the Russian pilots was provocative and dangerous, adding that "under the rules of engagement that could have been a shoot-down".