A former RAF pilot has suggested the appearance of Russian military planes off the south coast could be linked to the Litvinenko inquiry.
Andrew Brookes, a fellow of defence think-tank the Royal United Services Institute, said he wondered about the timing of their arrival on Wednesday.
The Foreign Office said the jets caused “disruption to civil aviation” as the flew along the English Channel tailed by RAF fighters.
RAF Typhoons were scrambled to escort the planes “throughout the time they were in the UK area of interest”, a spokeswoman said.
The incident was part of an “increasing pattern of out-of-area operations by Russian aircraft”, she added.
Russia’s ambassador was summoned to account for the incident.
Mr Brookes told BBC Radio 4’s Today programme: “They are basically strutting their stuff around the globe.
“Litvinenko ... I just wonder sometimes whether because of the timing of that inquiry this is somehow of associated with that.
“Just to say ‘you might have your way of doing things, but don’t forget we can still project our power the way we want to do it’.
“There is no threat, but it’s a massive disruption. It’s basically two fingers from the Russians.”
It was a way of saying that Russia is “still a force to be reckoned with on the world stage” that should be taken into account, he added.
The inquiry into the death of poisoned Russian dissident Alexander Litvinenko began this week.
He died from radiation poisoning in London in 2006, nearly three weeks after he drank tea laced with polonium.
The former KGB agent, who fled to the UK, was a vocal critic of the Kremlin and worked for MI6.