"The Russian prime minister, Dmitry Medvedev, has said Moscow would respond to any new western sanctions "asymmetrically," possibly preventing airlines flying through Russian airspace, if the US and EU press on with "the temptation to use force in international relations".
In an interview with Russian daily Vedomosti published on Monday, Medvedev said: "If there are sanctions related to the energy sector, or further restrictions on Russia's financial sector, we will have to respond asymmetrically."
The EU has agreed on new economic sanctions on Russia, which should come into force on Monday, but said they could be suspended to allow Moscow to show it was resolving the conflict in Ukraine that has killed nearly 3,000 people and caused the worst confrontation between Russia and the west since the cold war."
http://www.theguardian.com/world/2014/sep/08/russian-pm-warns-west-against-further-ukraine-sanctions