L to R: Turkish Foreign Minister Feridun Sinirlioglu, Secretary of State John F. Kerry, Saudi Foreign Minister Adel al-Jubeir and Russian Foreign Minister Sergei Lavrov met Oct. 23 in Vienna to discuss the Syrian conflict. (Carlo Allegri/AFP/Getty Images)

Iran will be invited to take part in a multi­national conference seeking a resolution to the civil war in Syria, in what would be the first instance of Tehran and Washington working together since the Iran nuclear deal was clinched.

State Department spokesman John Kirby would not tell reporters which country would issue the invitation to the meeting Friday in Vienna, but it is likely to be Russia. Iran’s supreme leader said this month that future negotiation with the United States is “forbidden,” despite the nuclear agreement, and it is not clear whether Tehran will attend.

Last week, Secretary of State John F. Kerry announced the meeting among countries that border Syria, are involved militarily in the conflict or are coping with an influx of Syrian refugees.

The talks will draw together diplomats from a dozen countries that have striking differences on potential solutions for the Syrian war — and whose relations with Iran range from warm to outright gelid.

Saudi Arabia and Iran, for instance, have long been regional rivals, and the countries have been lobbing bitter accusations at each other since more than 400 Iranian pilgrims died in a stampede last month in Mina outside of Mecca during the hajj.

Russia and Iran are the two biggest backers of Syrian President Bashar al-Assad, and both have launched military interventions in the country in support of his rule.

The United States, Turkey and Saudi Arabia are all adamant that the only way out of the morass is to ease Assad from power.

“The goal is to come up with a framework, an agreed-on multi­national framework, for a successful political transition in Syria which leads to a government not led by Bashar al-Assad, that is representative and answerable to the people of Syria,” Kirby said Tuesday.

Although the Syrian war is now in its fifth year, the push for an end to the fighting has gained new urgency in recent months with a wave of refugees fleeing the country and also abandoning camps in neighboring countries to head for Europe.

António Guterres, the U.N. high commissioner for refugees, said Tuesday that the crisis threatens to destabilize and even topple governments in countries bordering Syria that are burdened with too many refugees. That means that even countries with poor or no relations have an interest in collaborating on resolving the conflict, he said.

“Everyone understands the danger, not only to the region, but to global security,” he said during a visit to The Washington Post editorial board. “The differences [between countries], even if very important, represent less than the dangers we are all facing because of the Syria crisis.”

Guterres praised the idea of bringing together countries in a meeting like the one in Vienna.

“The United States and Russia are key conveners,” he said. “But there will be no solution if you don’t also engage Iran, Turkey and Saudi Arabia.”

Financial pledges at the recent session of the U.N. General Assembly to provide humanitarian aid and assist countries bordering Syria have allowed the Office of the U.N. High Commissioner for Refugees to restore some food aid cut in Jordan this year. Now, Guterres said, the UNHCR has 50 percent of what it needs to meet refu­gee needs worldwide, up from 40 percent before the session.

“With a crisis of this magnitude, the international response, financial and burden sharing, has been insufficient,” he said. “I’m not here to criticize, but we need more. We need more from Europe. We need more from North America. We need more from the [Persian] Gulf. We need more from everywhere.”