Russia would take military "countermeasures" if Sweden were to join Nato, according to the Russian ambassodor.
In an interview with Swedish newspaper Dagens Nyheter, Viktor Tatarinstev warned against joining the Nato alliance, saying there would be "consequences".
Decrying what he called an "aggressive propaganda campaign" by the media, Tatarinstev stressed that "Sweden is not a target for our armed troops".
But with a recent surge of Swedish support for joining Nato, the ambassador said: "If it happens, there will be counter measures.
"Putin pointed out that there will be consequences, that Russia will have to resort to a response of the military kind and re-orientate our troops and missiles.
"The country that joins Nato needs to be aware of the risks it is exposing itself to."
Despite the swing in public opinion - 31 per cent of Swedes wants to join Nato, up from 17 per cent in 2012 - Russia is confident that the country will not opt to join the Western military organisation.
He said: "I don't think it will become relevant in the near future."
Tatarinstev blamed souring Swedish-Russian relations on a media campaign in which "Russia is often described as an attacker who only thinks of conducting wars and threatening others".
Foreign Minister Carl Bildt referred to the former as "the most serious aerial incursion by the Russians" in almost a decade.
And Defence Minister Peter Hultqvist has since announced Sweden will be upgrading its navy fleet so it can better detect submarine activity.
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