U.S. Secretary of State John Kerry says he was alarmed at a video of Russian war planes flying dangerously close to a U.S. warship and will raise the matter directly with Russian Foreign Minister Sergei Lavrov.
State Department spokesman John Kirby said Thursday Kerry found the Russian maneuvers "unprofessional, needlessly provocative, and, indeed, dangerous."
Russia says its pilots observed all international rules when they flew over the USS Donald Cook in international waters in the Baltic Sea this week, near the coast of Kaliningrad.
The crew aboard the warship was dumbfounded to see the apparently unarmed SU-24 planes fly within 1,000 meters of the deck at an altitude of just 30 meters – close enough to create a wake in the water.
The Russian Defense Ministry said Thursday the planes were conducting test flights and only observed the Donald Cook before turning away, "in observance of all safety measures."
It said the U.S. ship was in "operational proximity of the Russian navy's Baltic fleet base." The Russian news agency Tass reported the ship was about 70 kilometers from the Russian naval base.
WATCH: Russian Jets 'Unsafe and Unprofessional' Flybys near US Ship
A U.S. State Department official said Thursday it is not unusual for Russia and other foreign aircraft to fly by U.S. ships to observe and says U.S. planes do it too.
"But it is highly unprofessional of what these two Russian pilots did - extremely low, extremely fast. I was personally stunned when I saw that video. I have not seen a pass like that in a very long time," the official told reporters.
A Pentagon official described the Russian flights as simulated attack passes. He said sailors on the Donald Cook attempted to reach the Russian planes by radio, but got no response.
Some military analysts say they believe the Russian maneuver may have come out of the Kremlin's resentment of a U.S. warship being so close to Russian territory.
NATO has bolstered its military presence in Eastern Europe as a response to the Russian annexation of Crimea in Ukraine in 2014.