WASHINGTON -- Authorities monitored a rush of intelligence leads Tuesday at the largest security operation in presidential inauguration history, including a possible threat from an East Africa radical Islamic terrorist group. Law enforcement and intelligence officials received information that people associated with a Somalia-based group, al-Shabaab, might try to travel to the U.S. with plans to disrupt the inauguration, according to a joint FBI/Homeland Security bulletin issued Monday night. The information had limited specificity and uncertain credibility, said Homeland Security spokesman Russ Knocke. U.S. counter-terror officials have grown concerned in recent months about the threat posed by the militant al-Shabaab...