【模仿句子】

But first much of Syria has been calm since the start of a nationwide ceasefire on Monday brokered by Russia and the United States. 

概况：叙利亚当地时间12日19时,美国和俄罗斯主导的最新叙利亚停火协议开始生效。初步消息表明,停火协议启动后,叙境内的冲突水平有所降低。