Top Russian military officials have accused Turkish President Recep Tayyip Erdogan of personally profiting from illegal oil trade with Islamist militants in Syria.

NPR's Corey Flintoff reports from Moscow that at a news conference, Russian military officials offered what they called evidence of oil smuggled to Turkey from ISIS-controlled fields in Syria. "They presented aerial photographs and satellite images that they say show long lines of tanker trucks carrying the oil to depots and refineries in Turkey," Corey says.

Erdogan strongly rejected the allegation, vowing to resign if Russia can prove it is true that Turkey — let alone Erdogan and his family — engages in trade with the self-proclaimed Islamic State.

Russia has accused Turkey of trading oil with terrorists before. But this accusation, from Russian Deputy Defense Minister Anatoly Antonov, goes further by alleging a direct connection to the Erdogan family.

"The main customer for this oil stolen from Syria and Iraq is Turkey," Deputy Defense Minister Anatoly Antonov is quoted as saying by The Associated Press. "The top political leadership of the country, President Erdogan and his family, is involved in this criminal business." The AP has more on Antonov's comments:

" 'Maybe I'm speaking too bluntly, but the control over that thievish business could only be given to the closest people,' Antonov said, adding that Erdogan's son heads a top energy company and his son-in-law has been named Turkey's energy minister." 'What a great family business!' Antonov said with sarcasm. 'Obviously, no one but the closest people could be entrusted to control such dealings.' "

The allegations are serious, Corey says: "Russia claims that ISIS makes about $2 billion a year from smuggled oil. So the Russians are accusing Turkey of helping to finance terrorism in Syria."

However, he says, Russia presented no evidence that Erdogan and his family were involved in such trade.

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