MOSCOW (AP) — When Syria broached the possibility of using chemical weapons, the world’s response was don’t even think about it. But one voice in that chorus mattered more for Syrian ruler Bashar Assad: Russia, his key ally.

Russia has been Syria’s key protector throughout the 16-month uprising that evolved into a full-blown civil war, shielding Assad’s regime from international sanctions and providing it with weapons despite an international outcry. And after the opposition attack last week that killed four members of his inner circle, the Syrian strongman may have to seriously think about a getaway scenario, for which Russia’s help will be essential.