Protests erupted around the Middle East on Saturday following the execution in Saudi Arabia of a prominent Shiite cleric, igniting sharp new tensions between Sunni and Shiite Muslims in a region already boiling with sectarian conflict.
Sheikh Nimr al-Nimr was one of 47 detainees put to death by sword and firing squad in the kingdom's largest such mass execution since 1980. The death of the popular cleric, who had been a critic of the Saudi government's often-harsh treatment of Shiites, touched off fury from Lebanon to Iran, with protesters storming and ransacking part of the Saudi embassy in Tehran and hurling Molotov cocktails at the consulate in the Iranian city of Mashhad.
In Bahrain, where a Saudi-backed Sunni-minority monarchy is ruling a Shiite-majority population, scores of protesters took to the streets before police fired tear gas to disperse the angry crowds.
The execution for what Saudi officials said were terrorism-related offenses was quickly condemned by international human rights organizations, with Amnesty International accusing the Saudi government of using the death penalty — carried out in 157 cases during 2015 — to "settle scores and crush dissidents."
The London-based group Reprieve said at least four of those executed were convicted of offenses related to political protest, and said the kingdom "is continuing to target those who have called for domestic reform."
The widening protests, along with Saudi Arabia's defiant move to carry out Nimr's October 2014 death sentence in the face of international condemnation, highlight increasing tensions between Sunni and Shiite Muslims that have fueled civil conflict throughout the region.
The execution comes at a time when Saudi Arabia is leading a coalition of forces from 10 Sunni Muslim countries against Shiite Houthi rebels in Yemen, even as the kingdom is providing financial backing for Sunni militias against the Shiite government of President Bashar Assad in Syria.
"The execution should be regarded in the context of this engagement. Saudi wants to show that not only is it fighting Shiites in neighboring countries, but also within its own borders," said Egyptian political analyst Mustafa Labbad, director of Al-Sharq Center for Regional and Strategic studies in Cairo.
"This execution will definitely have heavy consequences, even if [Nimr] is just a Saudi citizen who was executed by Saudi authorities," he added.
In addition to the sectarian rivalry simmering across the region, Saudi Arabia has also faced a wave of bombings and shooting attacks from Sunni extremists determined to overthrow the Saudi monarchy, which they have criticized as infected with corruption and beholden to Western allies such as the United States.
"Security forces will waste no effort in combating anyone involved with these terrorist groups," Interior Ministry spokesman Mansour Turki said at a news conference after Saturday's executions.
The ministry said 45 of those executed were Saudi nationals, with the other two coming from Egypt and Chad. All were convicted of plotting and carrying out terrorist attacks targeting civilians and security forces in Saudi Arabia and neighboring countries, along with planning to damage the nation's economy and harm its allies, the ministry said.
The BBC reported that one of those executed was Adel Dubayti, who had been convicted in a 2004 Al Qaeda-linked attack that killed Simon Cumbers, a freelance cameraman on assignment for the BBC. Reporter Frank Gardner was critically injured in the attack.
Nimr's nephew, Ali Mohammed Nimr, is also facing a death sentence in connection with the 2012 protests, which followed protests in 2011. But he was not one of those executed Saturday. Human rights groups have protested that sentence and at least two others imposed against suspects who were younger than 18 at the time of their arrests.
The most vociferous reaction to Saturday's executions came from Tehran, a sign of the increasingly hostile political rivalry between the two biggest power brokers in the Persian Gulf region.
"While extremists and … terrorists are threatening certain regional states, execution of a figure such as Sheikh Nimr who had no tool but speech to pursue his political and religious goals, shows deep imprudence and irresponsibility," Iranian Foreign Ministry Spokesman Hassan Jaber-Ansari said.
A picture posted on the Iranian Supreme Leader's website called Saudi Arabia the "white ISIS," using an acronym for Islamic State, and compared Nimr's execution to those carried out by the militant group against its opponents and captives.
Iranian state TV announced that all religious schools across the country would be closed for students to take part in protests of the execution.
Video footage and still photos posted on Twitter by a social media editor from Iran's Shargh Daily showed protesters inside one of the rooms at the embassy in Tehran, breaking glass and smashing furniture. Separate photos from the Iranian Students News Agency showed firefighters aiming a stream of water at thick smoke pouring out of the building.
Authorities were said to have safely evacuated the building and corraled the protesters.
Condemnations were triggered in Lebanon, where the country's Supreme Shiite Council called the mass execution a "grave mistake," and the Lebanese Shiite militant group Hezbollah, which is fighting Saudi-backed militias in Syria, called it an "assassination" and a "heinous crime."
In Iraq, parliament member Khalaf Abdul Samad called for the closure of the newly reinstated Saudi Embassy in Baghdad, while former Prime Minister Nouri Maliki said that executing Nimr is a "crime that will overthrow the Saudi monarchy."
Protests also erupted in Saudi Arabia's oil-rich Eastern Province, scene of the protests that formed the basis of Nimr's conviction and home to a majority of Saudi Arabia's Shiites, who account for up to 15% of the kingdom's population.
Thousands took to the streets when Nimr was shot and arrested in 2012.
Nimr was the most vocal opposition leader in the Eastern Province. He has called for and taken part in protests against the monarchy, and called prominently for the equality of Shiites, who live in the kingdom's main oil-producing area but have a generally lower standard of living and fewer freedoms.
Nimr has been arrested several times over the past decade, most recently during the Eastern Province protests, when he was charged with "breaking allegiance with the ruler," "inciting sectarian strife" and "encouraging, leading and participating in demonstrations."
In a letter reportedly sent to his mother during detention and widely publicized on Shiite news sites, Nimr was said to have welcomed the potential of becoming "a martyr" by way of execution.
"My mother, always thank God and accept what destiny writes, because the provision and destiny God provides is the best one and whatever he selects is the wisest one," it said.
U.S. State Department spokesman John Kirby said Washington has previously expressed its "concerns" about the legal process in Saudi Arabia and is reaffirming its call for protection of human rights and transparent judicial proceedings.
Kirby said Nimr's execution "risks exacerbating sectarian tensions at a time when they urgently need to be reduced."
The Saudi-based Arab News, quoting Saudi interior ministry officials, said the simultaneous executions Saturday were the biggest mass execution for such offenses since 1980, when 63 militants convicted of seizing the Grand Mosque in the holy city of Mecca in 1979 were put to death.
Special correspondents Hassan reported from Cairo and Mostaghim from Tehran.