The only state on the Security Council to vote with the United States was the Dominican Republic. All others abstained, meaning that the resolution failed. This diplomatic speed bump, however, will not stop the Trump administration from pursuing its goal of increasing pressure on Iran. Nor is it clear yet how Iran will react to these next steps.
The central question for the Security Council is whether the U.S., who has withdrawn from the nuclear agreement, has the standing to require the United Nations to reimpose the legal responsibility on states to tighten sanctions on Iran. The other members of the Security Council, most notably the EU3 (the UK, France, and Germany) say that Washington forfeited that right in 2018. The Trump administration clearly disagrees with this interpretation. The snapback is supposed to occur thirty days after a party to the agreement calls for it, which the U.S. just did even if only one other state agreed. This would put the deadline in late September, likely coinciding with President Trump’s speech to the annual meeting of the United Nations General Assembly. At that point, a stalemate will exist. The United States will say that United Nations sanctions are now legally back on Iran, and the rest of the Security Council will say that this is not so.
At the practical level, the international legal stalemate will have little impact. The United States has already re-implemented unilateral, national, sanctions on Iran. Given that many of these sanctions have secondary components – meaning that if a non-U.S. company conducts business with Iran they also could be subject to U.S. sanctions including exclusion from the U.S.-centered international banking system – very few if any companies have been making deals with Iran since May 2018. Few companies are likely to risk the secondary sanctions after the end of September either. While Iran will continue to attempt to smuggle its oil out to places such as Syria and/or Venezuela, it is not clear whether it will take any more steps than would take it outside of the nuclear agreement. It has not yet formally withdrawn from the agreement even though it has taken steps in its nuclear program that put it in violation of certain provisions.
The most likely outcome is that Washington keeps pushing and making pronouncements and that the rest of the world, including Iran, waits for the results of the U.S. election. A Biden administration, even if it is stuck with a Republican-controlled Senate, could revisit the nuclear agreement (which does not require Senate approval) but is still likely to be cautious, perhaps taking half measures such as allowing trade deals through waivers of the unilateral U.S. sanctions. A second Trump administration would make Iran and the EU-3 examine more closely how they can move forward without the U.S., including reconsidering ways to facilitate trade and investment outside of the reach of U.S. secondary sanctions. Iran could also choose, after the election, to abrogate the agreement fully and move more quickly towards a nuclear weapons capability.