The Boston Marathon bombing is another example of the US intelligence community knowing about the danger. The Russians rang us up and said "hey these two traveled to and from a known terrorist training camp", and everyone just shrugged.
Day-of, the bomb sniffing dogs left the finish line area when the VIPs did.
Day-of, the bomb sniffing dogs left the finish line area when the VIPs did.
Not long after, the bombers set up their bombs...