Washington Cnn) -- The travel advisory for Europe issued by the U.S. State Department was based on "potential threats" in Europe and "isn't related to the United States," White House press secretary Robert Gibbs said Monday.
"We are concerned enough to alert those in Europe to be aware" of the threat, Gibbs told reporters. He refused to discuss specifics of any terrorist plots.
"We have been tracking various threats for a while," Gibbs said. "I don't think this is tremendously out of the norm in terms of ensuring that those who are traveling in Europe are aware of what's out there."