RACHEL MARTIN, HOST:

Saudi Arabia executed 47 prisoners charged with terrorism yesterday. One death of a Saudi Shiite cleric has sparked sectarian outrage across the region and has further divided Sunnis and Shiites. Iran's top leader warned that Saudi Arabia would face divine revenge for executing the outspoken Shiite cleric. Protesters stormed the Saudi embassy in Tehran, setting fires and looting the building before police stepped in. NPR's Deborah Amos joins us now to talk more about this. Good morning, Deb.

DEBORAH AMOS, BYLINE: Good morning.

MARTIN: Deb, are Saudi officials surprised by the reaction to the execution of Nimr al-Nimr? I mean, they knew his position in the society. They had to have known that executing him would trigger some kind of big reaction.

AMOS: It couldn't have come as a surprise because this has been brewing since his death sentence in 2014. There were warnings from the region. There for appeals from Washington, from Europe, from the U.N. to spare this Shiite cleric. He's part of Saudi Arabia's repressed minority. He's been a persistent critic of the Saudi royal family. He often talked about the roar of the word - certainly not arms. The other people who were executed - they were members of al-Qaida. Very clearly, they had killed people - part of this bloody time in Saudi Arabia between 2003 and 2006. If they'd stopped there, they would have been no reaction. I talked to some Saudis today, and they were surprised by the execution. They said, look, it was a closed court. We really don't know what happened in that courtroom. And one said it shows that dissent can be punished by death.

MARTIN: The U.S. State Department yesterday issued a statement saying that the execution of this particular Shiite cleric could have dangerous consequences. This clearly complicates an already fraught relationship between the U.S. and Saudi Arabia.

AMOS: The criticisms have been coming not just from the U.S., but from the European Union. Germany issued a separate statement today. Nimr met with U.S. officials in 2008, and he wanted to show that he wasn't anti-American and that he wasn't pro-Iran. He became a leading Shiite figure in 2011. He was the voice of this revolt in the eastern provinces. It was part of the Arab Spring. This is a minority that's seeking rights in Saudi Arabia. He criticized Saudi autocrats, also in Bahrain. He also criticized the Syrian leader that's supported by Shia Iran. So he was an equal opportunity criticizer.

MARTIN: The demonstrations are expected to continue today, so how do you see this unfolding? What are the potential long-term consequences here?

AMOS: Yes, there are demos in Tehran. There's a funeral for Nimr in his hometown in the Eastern province in Saudi Arabia. Reportedly, his family was told his body has already been buried. You know, the region is in the grip of a sectarian fever. The wars in Syria, Yemen and Iraq are all based on this Sunni-Shia divide, so this makes things worse. Many people say that you cannot have a solution to these wars unless the Saudis and the Iranians come to some kind of understanding. When you listen to the rhetoric today, the top Iranian cleric is comparing Saudi Arabia to ISIS. The base of Sunni learning in Egypt is saying this is God's will - these executions. This rhetoric tells you that these conflicts will be even tougher to solve with these kinds of events over the past couple of days.

MARTIN: NPR's Deb Amos. Thanks so much, Deb.

AMOS: Thank you. Transcript provided by NPR, Copyright NPR.