Classified Ministry of Defence documents containing sensitive details about HMS Defender and the British military have been found at a bus stop in Kent.
A member of the public handed the defence papers to the BBC after realising the sensitive nature of the contents.
The documents included the likely Russian reaction to the ship’s passage through Ukrainian waters off the Crimea coast on Wednesday and plans for a possible UK military presence in Afghanistan after the US-led Nato operation there ends.
The government said an investigation had been launched.
The BBC believes the documents, which include emails and PowerPoint presentations, originated in the office of a senior official at the Ministry of Defence (MoD).
The documents relating to the Royal Navy’s Type 45 destroyer, HMS Defender, show that a mission described by the MoD as an “innocent passage through Ukrainian territorial waters”, with guns covered and the ship’s helicopter stowed in its hangar, was conducted in the expectation that Russia might respond aggressively.
On Wednesday more than 20 Russian aircraft and two coastguard ships shadowed the warship as it sailed about 12 miles (19km) off Crimea’s coast.
Moscow’s defence ministry said a patrol ship fired warning shots and a jet dropped bombs in the destroyer’s path but the UK government rejected this account, denying any warning shots had been fired.
The mission, dubbed “Op Ditroite”, was the subject of high-level discussions as late as Monday, the documents show, with officials speculating about Russia’s reaction if HMS Defender sailed close to Crimea.
“What do we understand about the possible ‘welcome party’…?” asked an official at Permanent Joint Headquarters (PJHQ), the UK’s tri-service headquarters at Northwood.
Recent interactions in the eastern Mediterranean between Russian forces and a Carrier Strike Group led by HMS Queen Elizabeth had been unremarkable and “in line with expectations”, the document said.
But officials knew this was about to change.
“Following the transition from defence engagement activity to operational activity, it is highly likely that RFN (Russian navy) and VKS (Russian air force) interactions will become more frequent and assertive,” one presentation warned.
UK “being scared”
A series of slides prepared at PJHQ shows two routeing options, one described as “a safe and professional direct transit from Odessa to Batumi”, including a short stretch through a “Traffic Separation Scheme” (TSS) close to the south-west tip of Crimea.
This route, one slide concluded, would “provide an opportunity to engage with the Ukrainian government… in what the UK recognises as Ukrainian territorial waters.”
Three potential Russian responses were outlined, from “safe and professional” to “neither safe nor professional”.
In the event, Russia chose to react aggressively, with radio warnings, coastguard vessels closing to within 100 metres and repeated buzzing by warplanes.
An alternative route was considered, which would have kept HMS Defender well away from contested waters.
This would have avoided confrontation, the presentation noted, but ran the risk of being portrayed by Russia as evidence of “the UK being scared/running away”, allowing Russia to claim that the UK had belatedly accepted Moscow’s claim to Crimean territorial waters.
The documents don’t stop there.
The bundle includes updates on arms exports campaigns, including sensitive observations about areas where Britain might find itself competing with European allies.
And there are briefing notes for last Monday’s session of the UK-US Defence Dialogue, including observations on President Joe Biden’s first months in office.
As the BBC’s diplomatic correspondent Paul Adams notes:
“Rarely has a collection of lost documents covered such a wide range of important areas.
“This is a major embarrassment for the Ministry of Defence, which is currently carrying out a detailed investigation into how the papers came to be lying on a street corner, in the rain, in the early hours of Tuesday morning.”
Related: Matt Hancock: The man with 9 lives