The Iran nuclear deal, otherwise known as the Joint Comprehensive Plan of Action, is not just a deal between the United States and Iran. Rather it is a multilateral deal involving seven countries: The USA, Iran, China, Russia, the UK,  France and Germany.  Five of those seven countries are permanent members of the UN Security Council and the JCPOA was both endorsed and activated by a unanimous vote of the Security Council in July 2015.

It was Security Council Resolution 2231 that made elements of the deal legally binding and gave the JCPOA broad-based international legitimacy.

With Trump’s decision today a veto-wielding permanent member of the Security Council has unilaterally abrogated a Security Council agreement. This is unprecedented. And a move like this will not just affect the JCPOA, but could have far reaching consequences for the viability of the Security Council as a multilateral platform to confront threats to global peace and security.

Anything that the US hopes to accomplish at the Security Council just got a bit harder.

The Security Council is an important platform for confronting threats to international peace and security. It is the the only entity in the world that can impose global sanctions and authorize military interventions. When members are divided — as in Syria today — its power is limited. When countries are unified, it’s power can be vast.

That power is derived not from passing resolutions. Rather it stems from countries feeling obligated and compelled to implement the decisions of the Security Council.  A Security Council resolution sanctioning North Korea or imposing an arms embargo on South Sudan is only valuable if countries enforce it.

This is why credibility matters. If the UNSC is seen as an valuable institution whose decisions are sacrosanct, countries are more likely to implement Council resolutions. If the UNSC is seen as toothless or otherwise unimportant, countries are more likely to ignore what the Council orders them to do.

The decision made by President Trump today was not necessarily to violate the Iran deal, but worse — to ignore it. The US is reverting to its pre-July 2015 policy.  In effect, the US is pretending that Resolution 2231 does not exist.

That is arguably the most dangerous thing about this move: being indifferent to a Security Council resolution (that it voted for just three years ago) opens up space for other countries around the world to simply pick and choose the resolutions to which they will abide and implement and which they will ignore. The power of the Security Council to confront threats to international peace and security has just been eroded by one of their own.