但是，由于美国在其所干预的地区受到了诸多挫折，而国内则正在饱受经济低迷之苦，因此在如何应对国际局势变化上，美国需要面临诸多不确定性。
But, in the aftermath of setbacks in regions where it intervened, and with heightened economic distress at home, the US finds itself uncertain about how to respond to changing global events.