Domestic political concerns, as well as tough losses suffered in nearly two years of regional conflicts and upheavals, appear to have led these Iran allies to take a back seat in the latest round convulsing the region.

President Donald Trump said Saturday that the U.S. military struck three sites in Iran, directly joining Israel’s effort to decapitate the country's nuclear program in a risky gambit to weaken a longtime foe amid Tehran’s threat of reprisals that could spark a wider regional conflict.