Saudi Arabia’s King Salman has dedicated his first year on the throne to bold and sometimes reckless moves to shore up the royal family’s power both at home and abroad. Now he has taken a step that was as risky as it was unjustified: the execution of a leading Shiite cleric who had spoken out for the kingdom’s repressed minority sect. It was an act that appears bound to further inflame conflict between Shiites and Sunnis across the Middle East.

Sheik Nimr Baqr al-Nimr was one of 47 men put to death Saturday. But unlike most of those killed, he wasn’t a Sunni militant with ties to al-Qaida.

Sheik Nimr excoriated the Saudi regime with biting rhetoric, but he was not an advocate either of violence or militant sectarianism. He favored elections as a means to reform Saudi Arabia and other Persian Gulf states and denounced the Shiite-backed Syrian regime of Bashar al-Assad.

By executing him, the Saudi regime managed to unite most of the world in condemnation. The potential for further violence was quickly evident in attacks on the Saudi Embassy and a consulate in Iran.

Iran, a world leader in executions, political imprisonments and sponsorship of terrorism, has little standing to protest Saudi violations of human rights. But the royal families’ allies, beginning with the United States, should be asking whether the Salman court is checking Iran’s expansionism, as it contends, or sowing chaos in an already-stricken region while undermining itself.