As Pravda.Ru reported, the US Mount Whitney command ship entered the Black Sea before. According to the US military doctrine, the Black Sea is within the US operational Sixth Fleet's area of responsibility. However, given international conventions, ships of non-Black Sea countries cannot be in waters of the Black Sea for more than 21 days.
The Russian military have already claimed that they would conventionally draw a bead on yet another missile destroyer of the US Sixth Fleet which enters the Black Sea along with the Bal and Bastion missile complexes. The Russian Aerospace Forces may also pay it a visit at open sea.
The points of view of Biden and Putin do not coincide in the understanding that the relations should be built on a mutually beneficial basis and coincidence of interests