Only weeks ago, Sunni Arab nations, led by Saudi Arabia and the United Arab Emirates, were still trying to bring President Bashar al-Assad of Syria back into the fold, urging him to break with a weakened Iran.
Mr. Assad had already been invited back into the Arab League, an association of Arabic-speaking nations in the region, 12 years after being expelled for his brutal crackdown on the Syrian opposition. Then in September, Saudi Arabia reopened its embassy in Damascus, after nearly a decade of broken relations, an indication of confidence that Mr. Assad was there to stay.
Even the European Union had begun to discuss dealing with Mr. Assad on questions of the migration of refugees.
But Mr. Assad hesitated to turn away from Tehran, even when Iran and Mr. Assad’s other main backer, Russia — which kept him in power — were weakened and stretched by wars in the Middle East and in Ukraine.