RAF jets were scrambled on Wednesday after two Russian military aircraft were seen off the Cornwall coast, the Ministry of Defence has said.
The Russian Bear bombers did not enter sovereign airspace, it said.
On the same day, Defence Secretary Michael Fallon warned that Russia's President Putin posed a "real and present danger" to three Baltic states.
Prime Minister David Cameron said the Russian action should not be dignified with "too much of a response".
He added: "I think what this episode demonstrates is that we do have the fast jets, the pilots, the systems in place to protect the UK.
"I suspect the Russians were trying to make some sort of a point."
BBC political correspondent Ross Hawkins said the appearance of Russian aircraft near the UK coast was a show of strength from the Russians, and such incidents were carried out with political intent because they would be reported on.
Our correspondent said it was part of a trend which had seen Russian aircraft flying close to UK airspace and there had also been concern about similar incidents in Europe.
