The State Department on Monday warned Americans traveling to Europe of an increased risk of terrorist attacks, particularly over the holiday season.

“Credible information indicates the Islamic State of Iraq and the Levant (ISIL the U.S. gov't acronym for ISIS or Da'esh), al-Qaeda, and their affiliates continue to plan terrorist attacks in Europe, with a focus on the upcoming holiday season and associated events," the travel advisory read.

The State Department urged travelers to avoid large crowds and exercise caution at tourist sites, festivals, large holiday events and outdoor markets. The agency also warned that these attacks can come with little or no warning

Terrorists have already carried out attacks in Belgium, France, Germany, and Turkey this year but the advisory warns of the potential for attacks throughout the continent.

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The State Department issued a similar alert in May warning that the larger number of tourists visiting Europe in summer months presented greater targets for potential terrorist attacks in public locations including, "major events, tourist sites, restaurants, commercial centers and transportation."

The end of the alert notes that “European authorities continue to conduct raids and disrupt terror,” and the U.S. is working closely with European allies on the threat from international terrorism.

The advisory is set to expire at the end of February.