Western leaders warned Syria on Saturday that they could launch further missile strikes if chemical weapons are used again, while the pre-dawn attacks were denounced by Damascus and its backers as illegal actions that would carry repercussions. But one major worry appeared to ease: That the coordinated attacks by the United States, France and Britain late Friday could have set off a direct confrontation with Syria’s most powerful military partner, Russia. At the Pentagon, the director of the Joint Staff, Lt. Gen. Kenneth McKenzie, said the more than 100 missile strikes delivered a blow to the “heart” of Syria’s chemical...