By Tsvetana Paraskova of OilPrice.com

Following this weekend’s attack by Hamas on Israel, the United States could re-freeze at any time the $6 billion for humanitarian purposes to Iran which was part of a prisoner swap last month, Bloomberg reports.

In September, five Americans imprisoned in Iran were officially flown out of Tehran as the U.S. unfroze some $6 billion in Iranian oil funds held for five years. The prisoner swap deal also included the release of five Iranian prisoners being held by Americans, two of whom plan to stay in the U.S.

The deal between Washington and Tehran reached in August pledged to give Tehran access to nearly $6 billion in frozen oil revenues on the condition that the funds be used for humanitarian purposes.

However, the U.S. Administration is now weighing the option to freeze those funds again, although there has been no official blaming of Iran for any role in the Hamas attack, yet.

Intelligence agencies haven’t found yet hard evidence that Iran was behind the attack, but they believe Iranian officials knew of a plot by Hamas to carry out some action in Israel, an anonymous U.S. official told Bloomberg on Wednesday.

Commenting on the $6 billion funds to Iran, John Kirby, National Security Council coordinator for strategic communications at the White House, told MSNBC this week “That money can be frozen at any time. We can stop any transaction.”

“None of it has been allocated. None of it has been spent. So it’s all still sitting in a Qatari bank, and that is an option that’s available to us,” Kirby added.

U.S. Treasury Secretary Janet Yellen said on Wednesday, referring to the $6 billion, “I wouldn’t take anything off the table in terms of future possible actions.”