Tensions between Russia and Turkey, already playing different roles in Syria's bloody civil war, escalated with the downing of a Russian warplane on November 24.<br />It's the most recent clash in a series of disputes between the two countries.<br />Russian President Vladimir Putin on Monday accused Turkey of shooting down the plane to protect secret oil trade with the terrorist group ISIS.<br />He said the plane was actually going to attack ISIS targets in Syria.<br />Turkish President Recep Tayyip Erdogan said the plane violated Turkish airspace.<br />He said he'll resign if Moscow can prove its claim.<br />"As soon as such a claim is proved, the nobility of our nation requires (me) to do this," Erdogan told reporters at the climate change summit in Paris on Monday.<br />But, he added, if the allegations are untrue, then Putin should resign.
