Russia claimed that they fired warning shots at a British destroyer violating their maritime border near Crimea. The UK has tried to disempower the Russians by claiming the alleged shooting didn’t happen.
What is clear is that this was a stunt by the British regime. Under the United Nations Convention on the Law of the Sea ships, including surface warships, are allowed the right of “innocent passage” within the 12 mile territorial limit which defines a country’s maritime border. As Craig Murray points out this British warship cannot by any stretch of the imagination have been innocently going anywhere. Even if it was en route to Georgia there was no need to edge just inside a disputed border. Staging political provocations is not “innocent passage”. As so often the British side are lying while accusing the Russians of “misinformation”. 
(Update: I’ve watched a video on Russian media showing the interactions between the British warship and a Russian patrol boat. Interestingly the Russian patrol boat explains that there is no “innocent passage” for a warship at this time. Later they explain that naval exercises are being conducted in the area. Under the UN Convention the shore party can control passage through their territorial waters for short periods e.g. for exercises. The British warship comes out with the line “are you threatening me” – like some playground conflict and, predictably enough, calls the Russian side “unprofessional”. It is obvious from the audio that the British action was carefully planned. One point for the British line: the story was that their boat was not fired on by the Russians. Merely there were some artillery exercises going on in the area. OK. But, in that case, what were they doing insisting on “innocent passage” through a firing range? That is not exactly “professional” is it?)
Why did the UK stage this stunt? The answer is not hard to find. The UK has just signed a juicy little deal with Ukraine to supply it with patrol boats and to help it rebuild its naval infrastructure.  (The arms are to be supplied by UK arms merchants Babcock International  though actual construction may involve other arms producers including US ones). The deal appears to be based on a loan.  To loan an impoverished country a large sum of money to buy weapons from you is usually a sign of a desperate need to gain some kind of influence. The deal was signed on board HMS Defender.  So – it is pretty obvious. This stunt by the British was a sweetener to this deal. After the signing HMS Defender would sail through Crimean (Russian) waters to provoke the Russians, as a gift to Kiev. This action put the lives of British servicemen at risk – in pursuit of what exactly? In pursuit of Britain’s post Brexit ambitions to be an independent “global player”. The navy is being abused. It is there to defend the country not to be used to stage political and commercial stunts.
Politics in Kiev still seems to be dominated by a fundamentally unrealistic idea. They are forever egging on NATO to start a war with Russia on their behalf to take back territory in which the populations very clearly overwhelmingly want to leave Ukraine and be part of Russia. The combining of this unrealistic policy with British post Brexit imperial dreams does not bode well for the security of this region. Two policies equally detached from sense and reality.
This could get nasty. The UK has threatened to repeat the stunt.  And the Kremlin has promised a robust response in defence of their maritime borders refusing to rule out any response if it happens again.  This shows the idiocy – and extreme immaturity – of the UK action. Now one side or the other stands to look weak – the UK if they don’t repeat the stunt and Russia if they allow it to happen again and do not provide a very robust response. Even if we accept the UK’s position – of not recognizing the Crimean referendum – and the consequent view that these waters still belong to Kiev, it remains the case that this action was foolhardy. Specifically; this action has done nothing to resolve the problem. It is perfectly open to the UK to continue to press Russia on the issue of Crimea, to work through the UN, to apply, if they like, economic pressure etc. (for example mirroring EU sanctions related to Crimea) but – military stunts? If the Russian side was blocking a vital economic artery that might have some logic to it; but they are not. The only reason to invade Russian territorial waters around Crimea is to stage a provocation. It will do nothing to bring Crimea back to Ukraine. It is like a schoolboy throwing rocks at the window of the staff room instead of organising a petition. This, regrettably, is the level at which the current UK government operates. The underlying ‘strategy’ is a desire to establish Britain as a major independent player on the world stage. Well; war with Russia would certainly do that.
As for the goal of bringing Crimea back into Ukraine – one wonders how any of these democrats in London are going to explain to the 80% of Crimeans who want to continue to be part of Russia how that is actually democratic.