Washington (AFP) - A Russian military jet that flew just feet from a US destroyer in international waters in the Baltic Sea could have been shot down under US rules of engagement, US Secretary of State John Kerry said.

Russian aircraft repeatedly buzzed the USS Donald Cook this week, including an incident on Tuesday when a Russian Su-24 jet flew 30 feet (nine meters) above the ship in a "simulated attack profile," the US military's European Command said.

Russia has denied the action was reckless or provocative.

Kerry, speaking Thursday, strongly disagreed.

"We condemn this kind of behavior. It is reckless. It is provocative. It is dangerous. And under the rules of engagement that could have been a shoot-down," Kerry told CNN Espanol in Miami.

Kerry added: "People need to understand that this is serious business and the United States is not going to be intimidated on the high seas."

"We are communicating to the Russians how dangerous this is and our hope is that this will never be repeated," Kerry said.

The Russian maneuvers began Monday while the destroyer was located about 70 nautical miles from the Russian base in Kaliningrad, a Russian exclave on the Baltic Sea.