Russian fighter jets made numerous low-altitude passes close to a US military ship in the Baltic Sea earlier this week, US defence officials said Wednesday.
According to the Pentagon, the Russian planes made the "aggressive" manoeuvres on Monday and Tuesday in close proximity to the USS Donald Cook, a destroyer, while it was in international waters.
A Russian military helicopter also flew a number of low-altitude circles around the ship on Tuesday, taking photographs as it flew, according to US media reports.
The SU-24 jets were unarmed, but flew as in a strafing position, coming as close as an estimated 10 metres from the ship, according to US media reports.
Deck landing drills were being conducted aboard the ship when the event occurred on Monday, said the US European Command, which oversees US military operations in the Baltic Sea.
A helicopter belonging to an unidentified allied country was refueling on the ship's deck when two Su-24s made numerous close-range and low-altitude passes.
"As a safety precaution, flight operations were suspended until the Su-24s departed the area," the statement said.
The helicopter passed over the ship on Tuesday and was followed about 40 minutes later by two Russian SU-24 jets making 11 low-altitude passes, the statement said.
"The Russian aircraft flew in a simulated attack profile and failed to respond to repeated safety advisories in both English and Russian," the statement said.
The commanding officer of the US ship considered the Russian actions "unsafe and unprofessional."
"We have deep concerns about the unsafe and unprofessional Russian flight maneuvers," the Pentagon said in a statement. "These actions have the potential to unnecessarily escalate tensions between countries, and could result in a miscalculation or accident that results in serious injury or death."
White House spokesman Josh Earnest acknowledged the Russians had flown "dangerously close" to the US Navy ship, and the moves were "entirely inconsistent" with peacetime norms and brought up "serious safety concerns."
The Donald Cook recently made a stop at the port of Gdynia, Poland, according to a statement from the US embassy in Poland.
"The presence of USS Donald Cook in the Baltic Sea demonstrates US Navy commitment to enhancing maritime interoperability and improving the security of NATO though Operation Atlantic Resolve," the statement said.