The united nations convention on the law of the sea, which both UK and RF have signed, means somewhere between 3 and 12 nautical miles from the coast is classed as a nations territorial waters, so a good chunk of it would be administered by the RF, but not the whole thing

https://en.wikipedia.org/wiki/United_Nations_Convention_on_the_Law_of_the_Sea

obligatory the USA has not signed onto this cinvention, despite citing FREEDOM of NAVIGATION every time they send their bloody warships anywhere