许多人认为，去年8月奥巴马在威胁对叙利亚发动导弹袭击的基础上有所退让，这使得俄罗斯总统普京放胆吞并了克里米亚。
Many argue that Obama’s climb-down from his threatened missile strikes against Syria last August emboldened Russian President Vladimir Putin to annex Crimea.