The Russian Foreign Ministry says Moscow will respond to the presence of a U.S. naval ship in the Black Sea with unspecified measures.
The USS Porter, a U.S. naval destroyer, entered the Black Sea on June 6 on a routine deployment, according to the U.S. Navy.
"Of course, this does not meet with our approval and will undoubtedly lead to response measures," said Andrei Kelin, a senior Foreign Ministry official.
Quoted by the RIA news agency on June 10, Kelin also said the deployment of U.S. aircraft carriers in the Mediterranean was a show of force which in his view deepened a chill in ties between Moscow and Washington caused by Russia's actions in Ukraine and Syria.
Kelin said such moves were designed to ratchet up tensions ahead of a NATO summit in Poland next month.
"It is all being done on the eve of the Warsaw NATO summit. It is a show of force," he said.