Since Mr Obama took office, the rate of threats against the president has increased 400 per cent from the 3,000 a year or so under President George W. Bush, according to Ronald Kessler, author of In the President's Secret Service. According to the book, intelligence officials received information that people associated with the Somalia-based Islamist group al-Shabaab might try to disrupt Mr Obama's inauguration in January, when the Secret Service co-ordinated at least 40,000 agents and officers from some 94 police, military and security agencies.