NEW YORK (NYTIMES) - The UN Security Council's rejection of US efforts to indefinitely extend an arms embargo on Iran underscored America's deepening global isolation on the issue of Iran.

But for the Trump administration, the vote could open a separate path to try to inflict maximum damage on Iran ahead of November's US presidential election.

For months, Trump administration officials have warned that if the vote to extend the embargo failed, the United States would try to invoke a provision built into the Obama-era nuclear accord to punish any Iranian violations by reimposing all sanctions lifted when the deal took effect.

That could include the prohibition of not just arms deals, but also oil sales and banking agreements. In theory, all UN members would have to adhere to the sanctions.

The provision, known as a snapback, would be devastating for Iran, which is already struggling with a moribund economy made worse by the coronavirus. Pursuing the snapback would also put the Trump administration at odds with America's allies, which vehemently oppose it as legally dubious and potentially destabilising to the region.

"The United States has every right to initiate snapback," Ms Kelly Craft, the US ambassador to the United Nations, said late on Friday (Aug 14). "In the coming days, the United States will follow through on that promise to stop at nothing to extend the arms embargo."

That could include trying to enforce the snapback sanctions unilaterally, without the support of allies.

A day after the vote, President Donald Trump vowed a tougher response to Iran.

"We'll be doing a snapback," Mr Trump said during a news conference at his New Jersey golf club. "You'll be watching it next week."

Secretary of State Mike Pompeo denounced the Security Council's decision to scuttle the embargo provision, describing it on Friday as "inexcusable".

"We will continue to work to ensure that the theocratic terror regime does not have the freedom to purchase and sell weapons that threaten the heart of Europe, the Middle East and beyond," Mr Pompeo said.

While Friday's vote was about the duration of the arms embargo, the heart of the dispute between the US and its opponents on the Security Council is the nuclear deal.

Signed in 2015, the deal freed up the Iranian economy by lifting sanctions in exchange for Iran agreeing to halt its nuclear program. The deal was President Obama's signature diplomatic achievement, and was backed by some of America's closest allies, Britain, France and Germany, as well as its strongest foes, China and Russia.

Mr Trump came into office vowing to dismantle the deal, insisting he could get a better one. But when he finally withdrew the US from the accord in 2018, it touched off a diplomatic conflagration that has at times escalated toward war.

Since then, Iran has exceeded nuclear enrichment limits set by the accord and launched covert attacks on US military targets, while the US has assassinated Iranian military leaders and proxies, including Qassem Soleimani, the leader of Iran's revolutionary guards.

The arms embargo was designed to prevent Iran from buying and selling weapons, including aircraft and tanks. It was due to expire in October, at which point Iran would legally be able to begin replenishing its arms stockpiles, something the Trump administration has said it would not permit.

Of the 15 countries on the Security Council, only one, the Dominican Republic, joined the United States in supporting the proposal. Britain, France and Germany - all abstained from the vote, making a promised veto by Russia and China unnecessary. Of the 15 countries on the Security Council, Russian and China voted against the proposal and 11 countries abstained.

Critics of the US position question whether the Trump administration, having withdrawn from the nuclear accord, has legal standing in any debate over its provisions - including the arms embargo and snapback. Having failed to live up to its end of the agreement, these critics say, the Trump administration cannot insist on having a say over whether Iran is remaining faithful to the deal.

The State Department is prepared to argue that the United States remains a "participant state" in the nuclear accord that Trump renounced - but only for the purposes of invoking the snapback.

In defending its pursuit of the embargo, Trump administration officials have argued that Iran has been violating the arms restrictions laid out in the 2015 nuclear agreement.

Western intelligence agencies along with UN officials have determined that missiles used in an attack on a Saudi Arabian oil facility last year were manufactured in Iran, as were weapons intercepted by the US Navy that were bound for Iran's Houthi allies in Yemen. Iran has dismissed the allegations.

Judging from the statements from US officials, the United States has little patience for continued debate over the embargo. Rather, Friday's vote could be seen more as a diplomatic formality the Trump administration felt it had to undertake as part of a broader effort to achieve its ultimate goal: killing the nuclear deal once and for all.

"The objective is to bury the deal and pressure the Iranians," said Mr Robert Malley, president of International Crisis Group and a former coordinator for the Middle East and Persian Gulf region in the Obama administration.