Saudi Arabia has cut diplomatic relations with its regional rival, Iran, after attacks on the Saudi Embassy and consulate in Tehran over the execution of a prominent Shi'ite cleric by Riyadh.
Saudi Foreign Minister Adel al-Jubeir announced the severing of ties late on January 3 and gave Iranian diplomatic personnel 48 hours to leave his country.
All Saudi diplomatic personnel in Iran have been called home after the kingdom's diplomatic compound in Tehran was attacked in the early morning hours of January 3, with intruders setting fires and throwing papers from the roof.
The moves come amid increasingly harsh rhetoric between Riyadh and Tehran, with Iran's supreme leader warning of "divine vengeance" for the execution of Sheikh Nimr al-Nimr.
Jubeir told a news conference in Riyadh that the Iranian regime had "a long record of violations of foreign diplomatic missions," dating back to the occupation of the U.S. Embassy in 1979.
He said such incidents constituted "a flagrant violation of all international agreements," and that Iran's "hostile policy" was aimed "at destabilizing the region's security."
Jubeir also accused Tehran of smuggling weapons and explosives and planting terrorist cells in the kingdom and other countries in the region.
He vowed that Saudi Arabia would not allow Iran "to undermine our security."
Saudi Arabia's civil aviation authority says all flights to and from Iran have been canceled.
Meanwhile, the United Arab Emirates (U.A.E.), an ally of Saudi Arabia, downgraded its diplomatic representation with Iran on January 4, recalling its own envoy from Tehran and reducing the number of Iranian diplomats it allows in the U.A.E.
Bahrain and Sudan on January 4 also announced they were cutting diplomatic ties with Iran.
Kuwait also condemned the attacks on Saudi diplomatic missions in Iran and expressed support for the kingdom, but stopped short of saying it would cut off diplomatic ties with Tehran.
WATCH: Shi'ite groups in Pakistan added their voices to protests around the world against Saudi Arabia's execution of prominent Shi'ite cleric Sheikh Nimr al-Nimr. Hundreds of protesters gathered in Karachi and chanted death to the Saudi royal family.
U.S. Secretary of State John Kerry called both countries' foreign ministers to urge calm.
The White House urged Saudi Arabia and Iran to not let their diplomatic spat derail talks to end Syria's conflict.
White House spokesman Josh Earnest said Washington was concerned about the situation and wanted Saudi Arabia and Iran to show restraint. He urged both nations not to inflame tensions or further sectarian conflict.
The UN envoy for Syria is heading to Saudi Arabia and Iran to gauge the impact of the rupture in relations between the two longtime regional rivals on efforts to end the Syrian conflict.
UN deputy spokesman Farhan Haq says Staffan de Mistura was en route to Riyadh and will visit Tehran later this week.
Turkey, another player in the Syrian conflict, urged both Saudi Arabia and Iran to ease tensions, saying the Middle East region is "already like a powder keg" and cannot withstand a new crisis.
Saudi Arabia, ruled by a Sunni-led royal dynasty, is engaged in a power struggle with Shi'ite-led Iran throughout the Middle East.
Both sides have used proxy forces to struggle for or maintain influence in places like Yemen, as well as Bahrain, Iraq, and Syria.
The standoff illustrates the kingdom's increased defiance of Iran across the region under King Salman.
During his reign, Saudi Arabia has led a coalition fighting Shi'ite rebels in Yemen and staunchly opposed regional Shi'ite power Iran, even as Tehran struck a nuclear deal in July 2015 with world powers.
The execution of Nimr, announced on January 2 by Saudi Arabia, was expected to fuel further outbreaks of proxy violence.
Nimr was a central figure in protests by Saudi Arabia's marginalized Shi'ite minority until his arrest in 2012 and later conviction on terrorism charges. His execution drew condemnation from Shi'a across the region.
WATCH: Thousands of people gathered in the Iraqi capital, Baghdad, to protest against the execution of a prominent Shi'ite cleric by Saudi Arabia.
In addition to Nimr, 46 others, including three Shi'ite dissidents and several Al-Qaeda militants, were put to death.
Speaking on Iranian state TV, Iran's Deputy Foreign Minister Hossein Amir-Abdollahian said that by cutting diplomatic ties, Riyadh could not cover up "its major mistake of executing Sheikh Nimr".
The United States called for leaders in the region to take "affirmative steps" to reduce tensions.
"We believe that diplomatic engagement and direct conversations remain essential in working through differences and we will continue to urge leaders across the region to take affirmative steps to calm tensions," an official of President Barack Obama's administration said.
Supreme Leader Ayatollah Ali Khamenei said in a statement on January 3 that Nimr "neither invited people to take up arms nor hatched covert plots. The only thing he did was public criticism."
Iran's President Hassan Rohani condemned Nimr's execution but also denounced attacks on the Saudi Embassy and consulate as "totally unjustifiable."
"The buildings should be legally and religiously protected in the Islamic Republic of Iran," he said.
The Iranian Revolutionary Guards Corps, a powerful, elite paramilitary organization, called the execution a "shameful act."
Ayatollah Ahmad Khatami, a member of Iran's Assembly of Experts, denounced the execution as a crime by Saudi Arabia's "infamous regime."
"This...blood will stain the collar of the House of Saud and wipe them from the pages of history," Khatami was quoted as saying on January 2.
In Iraq, where the Shi'ite-led government is close to Iran, prominent religious and political figures demanded that ties with Riyadh be severed.
Iraqi Prime Minister Haidar al-Abadi warned that Nimr's execution would have repercussions on regional security.
His predecessor, Nuri al-Maliki, said Nimr's execution would "topple the Saudi regime."
In Baghdad, hundreds of protesters organized by influential Iraqi Shiite cleric Muqtada al-Sadr, called for the severing of diplomatic ties with Riyadh. Young men burned U.S., British, and Israeli flags.
Thousands of Iraqis also demonstrated in the cities of Najaf and Basra.