Hasan Tosun/Getty Images Representatives of the U.S., U.K., Iran, European Union, Germany, France and China pose for a photograph after finalizing the Iran nuclear agreement in July 2015.

WASHINGTON ― The Senate voted unanimously on Thursday to extend U.S. sanctions on Iran for 10 years. Lawmakers hailed the 99-0 vote as a critical step in ensuring that the U.S. would keep its ability to quickly reimpose sanctions if Iran violates the nuclear agreement reached last year. But the Obama administration and several sanctions experts say the extension has no practical effect and risks further straining ties with Tehran.

The White House has expressed reservations about the utility and strategic wisdom of the legislation, but indicated the president will sign it into law.

“I expect the President will sign the legislation when it reaches his desk, and the Secretary of State will retain the authority to continue to waive all of the relevant nuclear-related sanctions authorized by the legislation,” a White House official told The Huffington Post.

The Iran Sanctions Act, passed in 1996, was set to expire at the end of the month. As part of the 2015 nuclear accord, the U.S. waived some of the sanctions on Iran that were authorized in the 1996 bill. Proponents of the extension argued that if they had let the bill expire, the U.S. would lose the ability to put sanctions back into place, making Iran less motivated to hold up its end of the deal.

“If the sanctions architecture has expired, then we have no sanctions which we can snap back,” said Sen. Bob Menendez (D-N.J.), a hawkish Democrat who opposed the nuclear accord and has co-sponsored a different bill that would authorize new sanctions on Iran in addition to extending the 1996 law.

Andrew Burton/Getty Images Sen. Bob Menendez (D-N.J.), one of the most outspoken critics of the Iran nuclear deal and one of few Democrats to vote against it, has led the push for additional sanctions against Iran.

The push for a clean extension of the 1996 sanctions, without any new provisions, was co-sponsored by 20 Senate Democrats, most of whom voted in favor of the nuclear deal last year. “Iran has to know that the threat of snapback sanctions is alive and well,” Sen. Chris Coons (D-Del.), a supporter of the nuclear agreement, said Thursday in explaining his vote to reauthorize the Iran Sanctions Act.

Critics of the nuclear deal praised the outcome of Thursday’s vote. “The ISA is a critical foundation of the Iran sanctions architecture, keeps the snapback option in place and underscores the importance of bipartisan steadfastness in the face of Iran’s continued non-nuclear malign activities,” said Mark Dubowitz, the executive director of the Foundation for Defense of Democracies.

But sanctions experts say that Menendez and his colleagues on Capitol Hill are vastly overstating the importance of renewing Iran Sanctions Act. Since it was passed in 1996, Congress and the White House have imposed a series of additional sanctions that have had a far greater impact on Iran’s economy. And even if the 1996 law expires, the president could unilaterally reimpose those sanctions under the International Emergency Economic Powers Act (IEEPA).

“The language of IEEPA give the President a virtual carte blanche in imposing restrictions on U.S. persons’ dealings with foreign individuals or entities,” wrote Samuel Cutler, a senior analyst at Horizon Client Access, an energy sector consulting firm. “Congressional action, rather than providing new authorities otherwise unavailable to the Executive, more often serves as a mandate for the administration to enact certain provisions,” he wrote.

That makes lawmakers’ vote largely a symbolic display of toughness toward Iran. The actual effects of the extension are “pretty limited” said Erich Ferrari, a lawyer who specializes in sanctions law. But it could create the perception in Iran that the U.S. isn’t committed to holding up its end of the nuclear agreement.

“The imposition or renewal of any sanctions are going to be spun by those parties to make it look as if the U.S. is imposing new or stricter sanctions,” Ferrari told HuffPost.

While the sanctions extension won’t kill the nuclear deal, it will send a message to Tehran that many in Washington are looking for ways to unravel the accord, said Elizabeth Rosenberg, a former Treasury Department official who is now a senior fellow at the Center For New American Security.

“Iranians understand that there are some who support ISA extension because they want to end the deal, and that certainly undermines their confidence in it and will to continue implementation,” Rosenberg wrote in an email. “It will undermine Iranian confidence, and European confidence in the American ability to stay committed to the deal, but it’s not a nail in the coffin.”

It will undermine Iranian confidence, and European confidence in the American ability to stay committed to the deal, but it’s not a nail in the coffin. Elizabeth Rosenberg, former Treasury Department official

With the election of Donald Trump, Tehran already has reason to question Washington’s commitment to the deal, known by the acronym JCPOA.

“Trump’s ambiguous-to-hostile approach may make the Iranians more nervous and more inclined to express their concerns than they would have been,” said Richard Nephew, a former Iran sanctions coordinator at the State Department. “But even then I think Iran will play this smart: loud complaints, no action that contravenes JCPOA in order to keep the international mood against the US.”

A bigger problem with the Iran Sanctions Act extension could come in 2024, when the U.S. will be obligated to terminate rather than temporarily suspend sanctions against Iran. If the extension gets signed into law, it will remain on the books until the end of 2026. “Assuming the deal lasts that long,” said Cutler, “we may be setting ourselves up for a legitimate fight between Congress and the President.”

Secretary of State John Kerry made a last-minute plea to Senate Democrats on Wednesday to vote against extending the sanctions, but the White House has stopped short of threatening to veto the bill.

“While we do not think that an extension of ISA is necessary, we do not believe that a clean extension would be a violation of the JCPOA,” said a senior administration official.

The Iran Sanctions Act extension puts the White House in a difficult position. “I don’t think the White House believed that Congress would have the discipline to just pass a clean authorization,” Tyler Cullis, a policy associate at the National Iranian American Council, told HuffPost, referring to efforts by lawmakers like Menendez to combine the extension with the introduction of new sanctions. If Congress had voted to authorize additional sanctions, said Cullis, the White House would have had an easier time justifying a veto.

This article has been updated to include comment from the White House.