"We buy oil from Iran and we purchase it in proper conditions," Turkish Foreign Minister Mevlut Cavusoglu said Tuesday. "What is the other option?"

Cavusoglu's comments raise the specter of yet another clash between the U.S. and Turkey, which is also in the final stages of an arms deal with Russia that could trigger American sanctions. Turkish officials, in both cases, have dismissed the U.S.' threat of sanctions to constrain the choices of other countries.

"While we are explaining why we will not obey these sanctions, we have also expressed that we do not find these U.S. sanctions appropriate," Cavusoglu said Tuesday.

The Trump administration hopes to isolate Iran and deprive the regime of access to international sources of revenue that might be used to finance a nuclear weapons program or regional aggression by the Iranian Revolutionary Guards Corps and the regime's terrorist proxies.