A Russian fighter jet made a dozen "provocative" close-range passes over a US warship in the Black Sea as tensions continue to ratchet up between the two superpowers over Ukraine, US military officials said.
A Russian Fencer jet buzzed the US navy destroyer USS Donald Cook a dozen times over 90 minutes, a Pentagon spokesman said.
"This provocative and unprofessional Russian action is inconsistent with international protocols and previous agreements on the professional interaction between our militaries," said Col Steve Warren.
The Russian jet allegedly flew within 1,000 yards (900 metres) of the American vessel at about 500ft above sea level.
Warren said several radio queries and warnings issued by the US warship were unanswered by the Russian aircraft crew.
The USS Donald Cook, which carries helicopters, has docked at the port of Constanta in Romania.
The incident came as fears that Russia is planning to invade eastern Ukraine continue to grow. It has amassed thousands of troops on its eastern border with Ukraine.
The US warship had arrived in the Black Sea earlier this month as part of a US effort to reassure allies in the region after Russia seized the southern Ukrainian peninsula of Crimea.