It was not immediately clear how Russia and China, who have veto rights in the Security Council and have publicly opposed a no-fly zone, would react to a call for action from a regional body; the more so since the call was, according to Omani Foreign Minister Youssef bin Alawi bin Abdullah, backed unanimously.
The more so 这里so是指代前面的内容,意思为”比这个更~~~”
看几个例句就清楚了
The new potentised strain of his discovery appalled him, and the more so because it contained dioxin as a by-product of manufacture.
他发现的植物新的有力应激反应使他胆寒,更加令人生惧的是这个过程包含了作为副产品产生的二恶英.
This is crucial, and all the more so as we navigate through the economic crisis