Federal officials have warned authorities in New York, Texas, and Virginia about the possibility of unspecified attacks by Al-Qaeda supporters near the November 8 presidential election.
A U.S. government source in Washington said on November 4 that some federal agencies had alerted state and local officials about the information but said the threats were low-level.
The Port Authority of New York and New Jersey said it had increased patrols around the airports, tunnels, and bridges in and around New York City that it operates.
CBS News first reported the threat of attacks, which it said were possible on November 7, the day before the presidential election.
The White House said on November 4 that it was "mindful" of the increased risk of attacks during events like Election Day, aware of threats of Al-Qaeda plots.
Texas Governor Greg Abbott said, "Texans should go about their daily lives as usual, but remain vigilant over the next several days and report any suspicious activity."
Officials said the threats might just be an attempt by a terrorist group to inspire someone to carry out an attack.
Based on reporting by Reuters and dpa