The stunning events of September 11, 2001, were a potential template for future terrorist attacks. But since then, al-Qaida and its affiliates have been unable to mount a similar encore in the United States. The foiled Times Square attack may be a sign that these groups have been forced to shift tactics to smaller operations that are less spectacular, but are also harder to detect. Former CIA counterterrorism chief Robert Grenier says the failed Times Square bombing last Saturday may indicate that al-Qaida and its allies have abandoned more grandiose plans for the United States and are emphasizing smaller but...