The United States has been increasing its presence in the Black Sea. USS Carney entered the water area of the Black Sea on February 17. According to representatives of the US Department of Defense, the purpose of the naval build up in the Black Sea is to reduce Moscow's sensitivity to the activity of US forces in the region.
The method that the USA resorts to to "reduce sensitivity" is rather strange, because it will most likely bring the opposite result, given that deputy head of the State Duma Committee for Defense and Security, Yury Shvytkin, said that the arrival of another US Navy destroyer in the Black Sea was a provocation.
Nevertheless, Washington believes that Russia will view the naval buildup in the Black Sea as a normal activity. Moreover, the neighborly presence of the military fleets of the two countries will help elaborate a better strategy of mutual behavior.
Washington has been trying to get Russia accustomed to its warships and warplanes for years already. In 2016, Pentagon officials said that Russia would have to get used to reconnaissance airplanes flying near its borders. Russia refused to get used to it, and sent a Su-27 to intercept P-8 reconnaissance aircraft of the US Navy.
USS Ross missile destroyer is also on a mission in the Black Sea. In the past, USS Ross attempted to make maneuvers near Russian maritime borders in the Black Sea. In 2015, Russia sent a group of Su-24 aircraft to the US warship, and the latter had to hastily retreat into neutral waters.
It is absolutely clear that Russia will never get used to the efforts of the United States or any other state to increase their military presence in the Black Sea. The Russian administration is well aware of the urgent need to strengthen the defense of the Crimea, and Russia will continue working in this direction to "calm and appease" Western "partners."
It seems strange, though, that Pentagon officials find Russia's moves to either scare off or intercept US warships and drones unacceptable and unfriendly. All in all, Russia has rich historical experience of "close interaction" with American warships on the Black Sea. For example, in 1988, six US warships violated the USSR's maritime border in the Black Sea. The US ships were immediately surrounded and driven out of the territory; one of the US ships was rammed. Luckily, no one was injured or killed.
The political aspect of the above is also important. Or rather, this is a very simple question and an obvious answer. If Russia had not reunited with the Crimea, where would it be? The US would have been the master of the Black Sea, and its warships would be as close to Russian borders as possible.