U.S. issues worldwide travel alert due to increased terrorism threats

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CHICAGO -- As Americans prepare to travel for the Thanksgiving holiday, the U.S. State Department has issued a rare, worldwide travel alert due to possible terror risks.

U.S. citizens are urged to be aware of their surroundings, and use caution at festivals and events.

Some travelers at O'Hare Airport on Tuesday said they can't live in fear, and aren't worried. Another traveler said there isn't much that can be done, and to just try to be safe.

In Europe, Brussels is on its highest alert: authorities fear what happened in France could next happen in Belgium.

Countries around the world are working to figure out how best to respond to ISIS -- from missile attacks, to the race for the White House.