The State Department issued a world-wide travel alert following a month of deadly terrorist attacks on three continents that have killed hundreds of people, including Americans.
Monday's alert, the first in nearly a year, expires on Feb. 24. It comes during the busiest U.S. travel week of the year, with millions of Americans hitting the roads and airways for the Thanksgiving holiday.
The State Department, in its warning, said terror groups including Islamic State and Boko Haram "continue to plan terrorist attacks in multiple regions. These attacks may employ a wide variety of tactics, using conventional and nonconventional weapons and targeting both official and private interests."
The State Department often issues travel warnings, but alerts are more uncommon, reserved for short-term events, whereas warnings can be indefinite and resulting from general instability.
Nonetheless, an alert doesn't mean a terror attack is imminent. It more likely reflects recent events -- such as the spate of terror attacks -- and the need for heightened caution.
A top concern for many intelligence officials is the risk posed by Islamic State militants who traveled to fight and train in Syria and Iraq and then returned to their home countries.
"Additionally, there is a continuing threat from unaffiliated persons planning attacks inspired by major terrorist organizations but conducted on an individual basis," the alert said.
Continue Reading Below