Originally Posted by
FODPlod
See here for chapter and verse on the ‘right of innocent passage’, even through the territorial waters of a Russian-invaded part of the Ukraine:
Article 17
Right of innocent passage
Subject to this Convention, ships of all States, whether coastal or land-locked, enjoy the right of innocent passage through the territorial sea.
You are omitting a well-known issue concerning prior notification. As there is nothing said clearly about this in the Convention, many countries in the world interpret in different ways. E.g., some UK Scandinavian neighbours require prior notification for warships:
Uncharted Waters: Non-innocent Passage of Warships in the Territorial Sea (sandiego.edu) page 641
AFAIK, a good friend of the US and UK, Saidi Arabia, clearly rejects any kind of innocent passage of warships.
I am sure that if the UK authorities "concerned with the issue" would behave as gentlemen and request such a passage, they would get "go ahead" no problem.
Another obvious point is "Ukrainian waters". Of course if anybody considers these waters as Ukrainian, it's their choice, but then get ready for tough attitude.
Imagine that a Russian sub appears near Falklands and "say" that "Argentinian government allows us to sail near Islas Malvinas". What would happen?