A Royal Navy warship was "sticking up for our values" in an incident with Russian forces in disputed waters around Crimea, Boris Johnson has said.
The prime minister said the UK does not recognise Russia's annexation of Crimea and was pursuing freedom of navigation in international waters.
Mr Johnson denied UK relations with Russia were at an all-time low.
He refused to be drawn on whether he had personally authorised the HMS Defender voyage.
But the prime minister said it was "wholly appropriate to use international waters" to "take the shortest route between two points and that's what we did".
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It was "very important" countries around the world continue to carry out manoeuvres "sticking up for our values, sticking up for what we believe in," he said on a visit to an Army barracks in Aldershot, Hampshire.
This would include "democracy, human rights, equalities and the rule of law, and freedom of navigation," Mr Johnson added.
On Wednesday more than 20 Russian aircraft and two coastguard ships shadowed HMS Defender as it was sailing off the coast of Crimea.
Moscow's defence ministry said a patrol ship fired warning shots and a jet dropped bombs in the Royal Naval ship's path.
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But the UK government rejected Russia's account of the incident and denied that any warning shots had been fired.
Defence Secretary Ben Wallace has set out the UK's version of what happened in a written statement to MPs:
10 minutes after HMS Defender entered the shipping lane inside Ukrainian territorial waters, a Russian coastguard had warned a "live fire gunnery exercise" would shortly begin
Eight minutes after that the Royal Navy ship "noted gunnery astern and out of range of her position", but this posed no danger to HMS Defender
Russian aircraft performed manoeuvres that were "neither safe nor professional"
"At no point were warning shots fired at HMS Defender, nor bombs dropped in her path as has been asserted by the Russian authorities," said the defence secretary.
The UK's defence attache was "invited to a meeting in the Russian Ministry of Defence" in response to the incident, he added, but HMS Defender would continue with her planned deployment and programme of visits.
"The Royal Navy will always uphold international law and will not accept unlawful interference with innocent passage," said Mr Wallace in his statement, adding that the UK and Nato allies had "enjoyed a routine maritime presence in the Black Sea for many years".