The danger for Mr Obama, as he seeks to overhaul the intelligence system, is that a fresh attack on the American mainland would immediately expose him to the accusation of being soft on terrorism.

• 当奥巴马总统试图对情报系统进行大检查时，他面临的一个风险是一场针对美国大陆的恐怖袭击会马上把他推向反恐无力的风口浪尖。