Crimea draws a bead on US Sixth Fleet flagship

The Mount Whitney command ship of the US Navy has entered the Black Sea. The Russian Black Sea fleet along with the Bal and Bastion missile complexes have immediately drawn a bead on it. Command of the US Sixth Fleet have not revealed goals of the Mount Whitney's journey. It may exercise cooperation with the NATO partners. Mount Whitney has already been in the waters of the Black Sea several times. Namely it delivered aid to Georgia in autumn 2008 and was on duty in the Black Sea during the 2014 Olympic Games in Sochi.
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.