Washington (CNN) -- A homeland security official said Monday that a bulletin went out a day earlier to state and local law enforcement agencies advising them that the State Department travel alert in Europe was issued based on intelligence they had already been made aware of.
The four-page bulletin, a copy of which was obtained by CNN, is titled "Al Qaeda Threat to Europe."
It says it was issued "to raise general security awareness and as part of our ongoing effort to provide information about any potential terrorist threat against the United States or our allies in Europe."
The bulletin says that private-sector security and law-enforcement agencies can use protective measures "to help disrupt or mitigate a terrorist attack in multiple phases -- during surveillance, target selection, target infiltration, and engagement with security forces."
The official said Department of Homeland Security sent classified and unclassified information to state and local law enforcement agencies, elected officials and other partners and briefed state homeland security advisers, directors of fusion centers -- formed to share intelligence within their jurisdictions and with the federal government -- and law-enforcement officials across the nation.
The department also is briefing representatives from the private sector, including hotels and commercial properties, regarding the threat environment.
The official said that the Transportation Security Administration continuously deploys threat-based security measures as a result of intelligence. Passengers should continue to expect an unpredictable mix of security layers that includes explosives-trace detection, advanced imaging technology, dog teams and patdowns, the official added.