Sir, The precise sequence of events concerning HMS Defender, the Royal Navy destroyer that has attracted the ire of the Russian navy in the Black Sea, remains contested (“Johnson: We’ll keep sailing off Crimea”, News, June 25). However, the principles at stake are hardly in doubt. The Royal Navy ship was not only rejecting Russia’s spurious claim of jurisdiction over Crimea and its adjacent waters. It was also making a stand against Russia’s broader policy of throttling Ukraine by seizing all nearby naval access points. As commentators wonder whether “Global Britain” is a slogan in search of a meaning, British naval assets are deployed on Europe’s eastern edges, in defence of Nato allies and friendly nations. The episode is also a reminder that engagement with Russia includes not only diplomacy but the occasional display of power.