Turkey on Monday called on Russia to prove its claim that the Turkish military shot down a Russian plane in an effort to protect its oil trade with ISIS. "You should put your documents on the table if you have any," Turkish President Recep Tayyip Erdogan said in response to Russia's President Vladimir Putin's statement claiming Turkey was buying oil from ISIS. Erdogan also vowed to step down if Russia' allegations proved to be true. Ankara maintains it shot down the Russian plane on the Syrian border after repeatedly warning the jet to leave its airspace. Moscow insists the plane did not cross the border and that it gave advance notice of its flight path to the U.S., Turkey's ally. A state department spokesman on Monday said the U.S. did not receive information on Russia's air operation.