The Hill, 13 Sep. 2016- A Republican congressman is asking the Treasury Department whether a recent cash payment to Iran could be used to fund terrorism, and how the department plans to keep that from happening.

Rep. Joe Wilson (R-S.C.) said he’s “gravely concerned with the nefarious possibilities” of what Iran could do with $1.7 billion in cash from the United States. He sent a letter sent Tuesday the Treasury under secretary for terrorism and financial intelligence, outlining his fears.

At issue is a payment made to Iran by the U.S. earlier this year to settle part of a 1970s lawsuit between the countries. The payment, converted into European cash and airlifted to Iran, preceded a prisoner swap between Iran and the United States.

Republicans have since accused the Obama administration of paying ransom for American prisoners and funding Iran’s terror sponsorship with untraceable money.

“By providing this regime with billions [sic] of dollars in untraceable foreign currency, the Administration is aiding the regime and criminals across the world in their perpetuation of financial crimes,” wrote Wilson.

Wilson asked for an explanation of the risk of that payment funding terrorism, how the Treasury could ensure it doesn’t happen and whether “your office can conclusively say that these funds will not be used for money laundering and terrorist activities.”