Putin is facing the possibility of defeat in Ukraine. It could mean Russia’s loss of Crimea. While he has been arguing that Crimea is naturally Russian, it was not part of the Russian Empire until 1783. In that year the city of Sebastopol was established by Potemkin, and the Black Sea Fleet (Черноморский флот) began.
By 2023, he risks losing Crimea, the sea of Azov and therefore the naval bases in which the fleet was established and set. Indeed before 2014, when Russia annexed the peninsula, the Black Sea Fleet rented its naval base from the Ukrainian State.
Both countries had signed a partition treaty of 1997 by which the Soviet Black Sea fleet was divided between Russia (87 percent) and Ukraine (13 percent). The unequal division was compensated by rent paid by Russia to Ukraine for the base at Sebastopol. This rent was used to lower the price of Russian gas to Ukraine. The lease was meant to end in 2017, then an agreement (the Kharkiv Pact) signed on 21st April 2010 assured that the lease would continue until 2042. It was signed by President Dmitri Medvedev of the Russian Federation and Viktor Yanukovych of Ukraine (later ousted in the Euromaidan protests of 2014).
The numerous agreements between Ukraine and Russia on this complex matter came to an end with the annexation of Crimea and the vote in the Russian parliament (State Duma) on March 31st, 2014, making them void and null.
If Ukraine takes Crimea, the Black Sea Fleet will be terminated.
The Baltic is now a NATO lake. With the removal of the Black Sea Fleet, Russia would no longer have any voice in the Mediterranean. The Turkish Straits would not need to be international waters (a provision designed specifically for the Soviet Union). Syria would no longer have any support from the Russian navy. The Mediterranean would become a NATO lake as well.
The possibility is an upheaval in itself.
The Russian navy has an important revolutionary aspect. The navy stationed on the island of Kronstadt (near Saint Petersburg) was part of the demonstrations in 1905 and 1906 and the revolution of February/March 1917. The working-class sailors rebelled against the noble officers. They also contributed to the Soviet fight against the white-Russian counter revolution. In 1921 they changed sides, fought against the Soviet government, and were defeated.
The navy voiced concerns about food-shortages, freedom of the press, and limitations to demonstrate public dissent.
The navy has lost two key operational areas: the Baltic Fleet is locked in Saint Petersburg and Kronstadt (and Kaliningrad). The Black Sea Fleet may simply cease to exist if Crimea becomes Ukrainian.
In all societies the armed forces allow the interaction between people of different backgrounds and ambitions. It is not a social melting pot, but a place where society’s concerns often emerge. The sailors of Kronstadt famously paid with their lives their worries about day-to-day life.
Putin may have forever lost Crimea to Russia and, in the process, he may have also terminated the Black Sea fleet.