The US Senate voted on December 1 to extend the Iran Sanctions Act (ISA) giving the president the authority to impose sanctions on Iran for another decade. The bill had already passed the house of Representatives. The ISA was enacted in 1996 (as the Iran and Libya Sanctions Act), reauthorized in 2006 and 2011, and is set to expire on Dec. 31, if not renewed. GOP lawmakers have unanimously opposed the agreement. Some Democratic senators reconsidered their stances, expressing support for extending the presidential authority to counter Iran’s «aggressive behavior.» President Obama is not expected to veto the motion because the scale of support indicates a veto would be easily overridden.

The measure ensures that the president could easily restore the sanctions, if Iran breached the Joint Comprehensive Plan of Action (JCPOA). The deal reached in July 2015 required Iran to cap its nuclear program in exchange for lifting of sanctions against it.

Iran has complied significantly reducing its nuclear infrastructure. It’s important to note that the implementation of the JCPOA began January 16 after the UN's International Atomic Energy Agency (IAEA) certified that Iran was meeting all its obligations under the deal. Other parties to the agreement – Russia, the UK, China, France, Germany and the European Union – have largely lifted the sanctions since the deal became effective. Non-nuclear sanctions have also been dropped, partially ushering Iran back into the global economy.

After taking office, Donald Trump may continue signing waivers to be reissued every 120 to 180 days or he may change the policy. The waiver related to nuclear sanctions remains in place under the reauthorized ISA but the deal is in jeopardy. US President-elect Donald Trump has said many times that he would scrap the nuclear agreement, calling it the «stupidest deal of all time». He said that dismantling it would be his «No. 1 priority» as president. The deal allows any of the countries that negotiated the deal to cancel it within 30 days, without a vote by the United Nations Security Council, if they flag a violation.

Non-nuclear sanctions related to terror-sponsorship, human rights abuses and ballistic missile activities are intended to remain in place under the JCPOA.

The GOP lawmakers support the idea of introducing new sanctions on Iran over human rights violations and terrorism, including the support of Hezbollah. Mitch McConnell, the Senate majority leader, calls for a review of the current policy on Iran.

Iran has threatened to resume its nuclear program if the bill goes through. The Iranian government described the Senate vote as a violation of the agreement. Iranian Supreme Leader Ayatollah Khamenei said recently the extension would be viewed in Tehran as a breach of the nuclear accord and threatened retaliation.

A US Senate vote to extend the Iran Sanctions Act (ISA) for 10 years shows the world that Washington cannot be relied upon to act on its commitments, said Iranian Foreign Minister Mohammad Javad Zarif. Iranian lawmakers said they want to introduce a measure to make the government resume nuclear activity.

Indeed, the prospect of US ultimate withdrawal from the JCPOA is not to be taken lightly. Congress can vote to reintroduce sanctions not waived or vetoed by the new president. President Trump may not renew waivers. The US could merely declare that Washington was no longer bound by the non-binding multilateral agreement based on the UN Security Council resolution. The United States can sneak out of the deal if the Congress overrides a presidential veto of a joint congressional resolution disapproving the JCPOA.

The consequences of Congress stopping the deal would be grave. The deal has the support of European parties to the JCPOA. The US will face a big problem trying to bring them to its side. If not, some sanctions will remain lifted and the West’s unity will be broken. It would put into question the ability of the United States to lead the reshaping of the world order on Western terms, by alienating Washington’s European allies. The move will rob Europe of any illusions about their ally at a time when support for US is already low. The EU will face a big challenge trying to convince the US and Iran not to leave. It will have a slim chance to succeed.

Russia and China will adhere to the JCPOA provisions. Defying other global powers will make Washington the odd man out while the rest of the world would continue to trade with Iran.

Slate cites Jeffrey Lewis, an expert on nuclear nonproliferation at Middlebury College and founder of the Arms Control Wonk blog, who says, «If the unity of the countries that negotiated the deal falls apart, «all of the safeguards that the IAEA has put in place under the deal will go away,» says. According to him, «The IAEA access will drop, and they will say that they are no longer in a position to verify the peaceful nature of Iran’s program. They just won’t have the access. You could end up with a situation in which there are no sanctions, and we have no idea whether they’re building a bomb or not. And by the time we figure it out, it might be too late.»

As a party to the Iran deal talks, Russia is a member of the Joint Commission established to monitor the implementation of the agreement and resolve any disputes that may emerge. As such, it can influence the process of compliance. Moscow has the right to co-decide on the sanctions imposed by the Security Council and the unilateral sanctions adopted by the United States. This right is envisioned by the JCPOA.

No matter what the US does, Russia retains the right to export weapons to Iran on condition that contracts are reported to and verified by the UN Security Council. It has already sold S-300 air defense systems to Tehran.

A decision to tear up the deal will most certainly provoke Iran into reviving its nuclear weapons program. It could lead to a regional arms race. Saudi Arabia has already made known its intention to acquire nuclear capability. Israel – a US skittish regional ally – may consider striking Iran – a decision fraught with grave implications.

Donald Trump has said many times his prime goal in the Middle East is ousting Islamic State (IS). This stance has vast support in Congress. Iran is a member of the coalition fighting the extremist group. If the US joins Russia in fighting IS – something the US president-elect said many times he wanted to do – it will need Tehran onside.

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The US Congress has taken a step to destroy a deal enshrined in a United Nations resolution. «Say goodbye to the Iran deal», said Richard Nephew, a former US negotiator with Iran now at Columbia University. «There is very little likelihood that it stays, either because of a deliberate decision to tear it up by Trump, or steps that the US takes which prompt an Iranian walk back.»

The move entails harsh consequences. The Senate vote has undermined the US credibility as a reliable partner. Some of them mentioned above definitely prove that Congress does a disservice to its country reducing its national security and international standing.