United Nations chief Ban Ki-moon has asked Saudi Arabia and Iran to avoid actions that could further exacerbate tensions, as he expressed disappointment at the execution of cleric Sheikh Nimr Baqir al-Nimr and said the break in Saudi diplomatic ties with Iran was deeply worrying.
Al-Nimr's death was a dramatic step because Saudi Arabia has rarely resorted to the death penalty in dealing with unrest among its Shiite minority, which has long complained of discrimination in the Sunni-led kingdom.
Saudi Arabia cut ties to Iran after attacks on two of its diplomatic posts in the Islamic Republic following al-Nimr's execution.
On Tuesday, Kuwait announced the recalling of its ambassador in a statement carried on the state-run Kuwait News Agency. But he said that it's up to leaders in Tehran and Riyadh to stem the tensions, without the United States forcing the issue.
"The conflict between Iran and Saudi Arabia will definitely have a negative impact" on the peace process, said Samir Nashar, a member of the Syrian opposition-in-exile.
The toppling of Saddam in 2003 upturned the regional power balance, however, as Iran used its ties to the country's large Shi'ite community to gain sway in Baghdad, pitting Riyadh and Tehran more openly against each other - a pattern repeated in Yemen and Syria after the "Arab Spring" uprisings.
While the general impression is that the executions were a Sunni revenge for similar executions in Iran - which is a top-ranking country when it comes to awarding capital punishment - some commentators pointed out that only four of those executed by Saudi Arabia were Shias.
"From our side it should have no effect because we will continue to work very hard to support the peace efforts in Syria, in Yemen", he told reporters.
The ransacking of the Saudi embassy in Tehran and the Saudi consulate in Mashhad drew condemnation from around the world.
The Saudi decisions in Syria and Yemen were also partly a response to Iran's nuclear deal with world powers, which lifted sanctions on Tehran, theoretically giving it more money and political room to pursue its regional activities.
But rich on its new oil wealth, Saudi Arabia began to propagate its rigid Salafi interpretation of Sunni Islam which regards Shi'ism as heretical, in mosques around the region. Iran supports a negotiated solution to differences of opinion between countries.
"While we certainly want to foster that engagement, I think you can all understand that real, long-term sustainable answers are not going to be legislated from Washington", Kirby said.
And he compared Riyadh's "immature reaction" to the attacks with Iran's "restraint" after 464 Iranian pilgrims died in a stampede at the hajj in Saudi Arabia in September.
Some nations have followed the Saudis' lead in severing or downgrading ties with Iran, while others have offered words of caution aimed at calming the situation.
The growing rupture between Saudi Arabia and Iran is threatening US efforts to end the Syrian civil war and stop ISIS in the Middle East.
"There have been direct concerns raised by U.S. officials to Saudi officials about the potential damaging consequences of following through on the execution, on mass executions, in particular, the execution of" Nimr, Earnest said. But the cutting of diplomatic ties has shone a spotlight on Iran once again storming an embassy, reinforcing the image of the country as a revolutionary theocracy.
Saudi Arabia's U.N. Ambassador Abdallah al-Moualimi said late Monday tha tSaudi Arabia will attend the January 25 talks in Geneva on Syria.
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