The Pentagon on Monday criticized a Russian jet's repeated buzzing of a U.S. antimissile ship sailing in international waters in the Black Sea.

The action happened on Sunday and involved a nuclear-capable -- but unarmed -- Su-24 fighter aircraft that made a total of 12 flying passes close to the Aegis-equipped USS Donald Cook while it conducted patrol operations in the western Black Sea, the Defense Department told reporters.

"The aircraft did not respond to multiple queries and warnings from Donald Cook, and the event ended without incident after approximately 90 minutes," department spokesman Army Col. Steve Warren was quoted as saying in a Pentagon press story. "This provocative and unprofessional Russian action is inconsistent with international protocols and previous agreements on the professional interaction between our militaries."

A second Su-24 accompanied the first Russian fighter jet but did not make any passes, Warren said.

The U.S. missile destroyer was redeployed to the Black Sea in recent days in accordance with the Pentagon's efforts to assure NATO members and other countries of a U.S. commitment to their security. The ship's deployment comes amid continuing tensions with Russia over Moscow's annexation of Ukraine's Crimean Peninsula and suspected involvement in insurgent actions in the eastern part of the country.

The USS Donald Cook is home-ported in Rota, Spain, and is the first of four Aegis ships slated for deployment in the Mediterranean as part of the U.S. contribution to NATO missile defense.

"The Donald Cook is more than capable of defending itself against two Su-24s," Warren said.

The Russian defense ministry last week spoke out against the deployment of the warship to the Black Sea, saying it demonstrated that U.S. antimissile systems in Europe are aimed at undermining Russia's nuclear deterrent.

Warren suggested the Su-24 pilots were acting with some form of approval from the Russian military. "I would have difficulty believing that two Russian pilots, on their own, would choose to take such an action," the spokesman said.