A worldwide travel alert was issued by the U.S. State Department for Americans Monday.
It says authorities believe the likelihood of terror attacks will continue as members of ISIS return from Syria and Iraq.
ABC’s Chief White House Correspondent Jonathan Karl in Washington…
Karl: “Officials have made it clear to us they are not telling Americans not to travel around the world but to be vigilant. They’ve offered a few tips. Tips include U.S. citizens should exercise vigilance in public places when using transportation. Two, be aware of immediate surroundings and avoid large crowds or crowded places and finally exercise particular caution around the holidays.”
The Department’s alert states that the U.S. is continuing to work with allies on the threat of international terrorism: “Foreign governments have taken action to guard against terrorist attacks, and some have made official declarations regarding heightened threat conditions.”