The lack of communication between various federal agencies in cases related to counter-terrorism, long before, before and after 11/9 was often criticized, scrutinized and analysed, without any positive results.
The security concerns increased, the number of agencies increased, the bureaucracy as well. But not at all the level of information sharing. In many situations, the terrorists entering to or intending to enter the territory of the USA were having valid passports and valid visas. Maybe, in some cases, according to the consular services, there were not qualified as immigrants so got freely the visa. They do not even try to access the visa waiver service, but follow the very bureaucratical and for many, unsuccessful way.
Too many challenges, too many agencies, too much bureaucracy, too much insecurity.