1) Dan Sabbagh (Defence and security editor), “Royal Navy ship off Crimea sparks diplomatic row between Russia and UK; MoD and Moscow disagree over whether shots were fired at destroyer near disputed territory,” The Guardian, June 23, 2021 (19.08 BST).
2) Valerie Hopkins, Ivan Nechepurenko, and Isabella Kwai, “British Warship Deliberately Sailed Close to Crimea U.K. Officials say: The action, meant to demonstrate support for Ukraine, incited an international incident after Russia scrambled warplanes and Coast Guard vessels,” New York Times, June 24, 2021 (updated 3:53 p.m. ET).
It is important to understand the international law context in considering the significance of a British warship transiting the territorial sea along the coast of the Crimea, and being harassed by Russian military forces.
Russia conquered the Crimea by military force in February and March 2014. Later in March, Russia purported to annex the territory of the Crimea it had conquered by the illegal use of force in contravention of Article 2 paragraph 4 of the United Nations Charter.
Article 2 (4) is a norm of jus cogens or peremptory international law, from which there can be no derogation by agreement, not even by a treaty.
Consequently, the territorial sea off the coast of the Crimea, which under international law remains part of Ukraine, belongs to Ukraine, and Russia has no legal authority to regulate passage through what are Ukrainian waters.
The British warship was undoubtedly asserting its rights under international law, including the U.N. Convention on the Law of the Sea.
Russian actions, purportedly in defense of its sovereignty, were in fact a continuation of its illegal aggression against the Ukraine.
The Trenchant Observer