Tehran has not confirmed allegations that it uses ship-to-ship transfers or regional intermediaries to mask the origin of its oil.
According to reliable sources, the existing waiver expired on Tuesday, but following intensive negotiations, India succeeded in obtaining an extension from Washington.
Trump's decision to hit Russia with sanctions capped a tumultuous week with respect to the administration's Ukraine policy.
U.S. sanctions generally prohibit American individuals and companies from engaging in any business transactions with those targeted.