The greatest increase in tensions , however , came during the Ukraine crisis that began in 2014 , which saw the Crimean peninsula annexed by Russia . Russia also inflamed a separatist uprising in the Donbass region , though Moscow continues to deny its involvement . The United States responded to these events by putting forth sanctions against Russia , and most European countries followed suit , worrying about Russian interference in the affairs of central and Eastern Europe . October 2015 saw Russia , after years of supporting the Syrian government indirectly , directly intervene in the conflict , turning the tide in favor of the Assad regime . Russia 's relations with Turkey , already strained over its support for the Assad regime , deteriorated further during this period , especially after the Turkish Air Force shot down a Russian jet fighter on 24 November 2015 . In 2015 , Russia also formed the Eurasian Economic Union with Armenia , Kazakhstan , and Belarus
shot down
2015 Russian Sukhoi Su-24 shootdown
Foreign relations of Russia