If Western sanctions and diplomacy fail to curb Iran's nuclear program, Tehran's use of Turkey to swap oil for gold in recent years may be seen as a primary reason.
U.S. lawmakers on Tuesday quizzed Obama administration officials and outside analysts during a Capitol Hill briefing about why Iran was able to use Turkish banks to skirt sanctions and repatriate as much as $100 billion in oil revenues to Tehran.
The trading scheme is widely seen today as the largest hole that emerged in the West's sanctions regime against Iran. And U.S. officials are voicing concerns that Iran is developing a similar scheme with Russia to swap sanctioned Iranian oil for outside goods.
"The conclusion of the long saga is that Iran was able to exploit a significant golden loophole, was able to get about $13 billion in gold and over $100 billion in illicit financial transfers and ultimately blow a major hole in the international financial sanctions regime," said Mark Dubowitz of the Foundation for Defense of Democracies, a conservative Washington think tank.
"I think we didn't crack down on Turkey and perhaps that is because of President Obama's partnership with Prime Minister [Recep Tayyip] Erdogan. My fear is that on the Iran-Russia deal we will face the same situation," he said.