It's time for the United States to hold Iran accountable.

WASHINGTON –  In an unexpected reversal, President Barack Obama declined to sign a renewal of sanctions against Iran but let it become law anyway, in an apparent bid to alleviate Tehran's concerns that the U.S. is backsliding on the nuclear deal.

Although the White House had said that Obama was expected to sign the 10-year-renewal, the midnight deadline came and went Thursday with no approval from the president. White House press secretary Josh Earnest said Obama had decided to let it become law without his signature.

"The administration has, and continues to use, all of the necessary authorities to waive the relevant sanctions" lifted as part of the nuclear deal, Earnest said in a statement.

Under the Constitution, the president has 10 days after Congress passes a bill to sign it, veto it or let it become law with no signature if Congress is still in session. Although lawmakers have returned home for the holidays, Congress technically has not adjourned and is holding "pro-forma" sessions this week.

Though Obama's move doesn't prevent the sanctions renewal from entering force, it marked a symbolic attempt by the president to demonstrate disapproval for lawmakers' actions. The White House has argued that the renewal is unnecessary because the administration retains other authorities to punish Iran, if necessary, and has expressed concern that the renewal may undermine the nuclear deal.

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