Air defence missile systems will be sent to Russia's air base in Syria, government leaders have said.
After a Russian fighter jet was shot down by Turkey amid allegations the Russians had violated their airspace, news agencies reported President Vladimir Putin as saying advanced, long-range anti-aircraft surface-to-air S-300 missile system would be deployed to the region.
Meanwhile, Defence Minister Sergei Shoigu said the newer version - the S-400 missiles - would be sent, to be stationed at Hemeimeem air base from where Russia is conducting its aerial bombing campaign in Syria.
Putin also accused Turkey's political leaders of supporting a "deliberate policy of Islamisation" of the country, saying he believed that was part of the problem.
Turkey has shown it is willing to take on Russia after downing a Russian fighter jet.
This incident will leave the American military profoundly alarmed that the Syrian conflict is now threatening to spiral out of all control.