Moscow warned the U.S. Navy to stay away from Crimea "for their own good," and called the deployment of U.S. warships to the Black Sea a provocation while suggesting that the United States was an adversary.

The U.S. Navy had notified Turkey – a NATO ally, but one with a complicated relationship – that a pair of warships could sail to the Black Sea a few weeks back. The plans were eventually scrapped.

Black Sea: A Flashpoint with Russia? 

Despite the pullback from the Biden Administration, the Black Sea is clearly becoming a sour spot in U.S.-Russia and NATO-Russia relations.

The United States has increased such visits to the Black Sea, which requires passage through Turkish waters including sailing past Istanbul. The increased presence of the U.S. Navy near its territorial waters has incensed Moscow.

"There is absolutely nothing for American ships to be doing near our shores, this is purely a provocative action. Provocative in the direct sense of the word: They are testing our strength and playing on our nerves," said Russian Deputy Foreign Minister Sergei Ryabkov to reporters earlier in the week.

"Seeing itself as the Queen of the Seas, the U.S. should realize that the risks of various incidents are very high. We warn the U.S. that it should stay away from Crimea and our Black Sea coast for their own benefit."

The deputy foreign minister was even more direct in how Moscow now views such actions by the United States.

"The United States is our adversary and does everything it can to undermine Russia's position on the world stage," he added. "We do not see any other elements in their approach. Those are our conclusions."

Moscow has vowed to take measures to guarantee its own security in the Black Sea.

"Stepped-up military activity by the NATO bloc, and the U.S. in particular, in close proximity to Russia's borders in the Black Sea region has been determined," Russian Security Council Secretary Nikolai Patrushev said on Wednesday during a session dedicated to guaranteeing national security in Crimea, as reported by Tass.

"The question is, what does the US have to do with the Black Sea," added Patrushev. "What national interests are they pursuing here, if many Americans have no idea where this sea is?"

Russia had annexed Crimea from Ukraine in 2014, and its Black Sea Fleet is based on the peninsula. Additionally, the Russian military has housed missile and radar facilities there.

The U.S. warships were slated to to arrive in the Black Sea amid an escalation in fighting in eastern Ukraine, whereas Reuters reported, government forces are engaged with Russian-backed separatists.

To date, more than 14,000 people have reportedly been killed. Ukrainian forces have U.S. and European support.

Pentagon spokesman John Kirby did not comment on the deployment of the warships to the Black Sea, but said in his press briefing last week that the U.S. Navy "routinely" operates in the Black Sea.

Peter Suciu is a Michigan-based writer who has contributed to more than four dozen magazines, newspapers and websites. He regularly writes about military small arms, and is the author of several books on military headgear including A Gallery of Military Headdress, which is available on Amazon.com.