Russia's foreign minister said Friday that his country will take action at its northern borders should Sweden join NATO, amid an ongoing debate in Sweden and neighbouring Finland on the merits of NATO membership.
In an interview with Swedish daily Dagens Nyheter, Sergei Lavrov said "each country has the right to form its own security, but you have to understand that if military infrastructure comes closer to Russia's borders, we will take the necessary military technological measures."
Lavrov added there was "nothing personal in that, it's just business."
Finnish Foreign Minister Timo Soini on Friday received a report from an expert panel, which since January had been analysing the possible consequences of Finland's membership in NATO.
"Russia would react quite strongly were Finland and Sweden to join NATO," said panel member Francois Heisbourg, chairman of the London-based International Institute for Strategic Studies.
He said the group was not tasked with recommending a course of action for Finland.
However one of their findings was that Finland and Sweden should opt for the same solution, since only one of the two neighbouring countries joining NATO would weaken the other.
Finnish membership in NATO would also double the length of the alliance's border with Russia, and Moscow was expected to respond to this with strong protests and sanctions, the report said.
Soini said Finland had no current plans to apply for NATO membership and described the 64-page report as recommended reading.
Sweden, which already has close ties with NATO, has also commissioned reviews on the consequences of applying for membership, although there is no consensus between the government and the main opposition on seeking a membership with the 28-member joint defence alliance.
"We have always warned against NATO's ongoing expansion to the east," Lavrov said.
Swedish Foreign Minister Margot Wallstrom responded to the remarks on Twitter, saying "Sweden's security policy is determined by Sweden, no one else."
Annie Loof, leader of the opposition Centre Party, labelled Lavrov's comments as "appalling" and said Sweden's foreign and security policy was not determined by "Russian threats."
Lavrov said Russia was "not interested in increased military confrontation," but added that it was up to Russia's military, defence ministry and chief of staff to decide how to act if Sweden joined NATO.
"NATO says there is no intent to do anything adverse to Russian security. But if there is no such intent, why deploy military infrastructure at our doorstep? In such a situation we can't act on stated intent but the reality we see with our own eyes," Lavrov said.
NATO suspended practical cooperation with Russia in 2014 after the Crimean peninsula was annexed by Moscow, amid claims that Russia was supporting a rebellion in eastern Ukraine.
Lavrov expressed regret at the halt of joint maneuvers with NATO aimed at "combating terrorism" more effectively.
Lavrov also rejected suggestions that the Russian military had been acting dangerously amid reports of close encounters with vessels and aircraft from other nations in the Baltic Sea, most recently a low-altitude pass by Russian jets near a US Navy vessel.
"Our planes were on a legitimate training mission in the area, in international airspace," Lavrov said, commenting on the US Navy incident.
"They spotted the heavily armed US vessel that was approaching our military base and decided to take a closer look. When they saw what it was, and this was at a safe distance, they turned around and continued their exercises," Lavrov said.