The State department tweeted its travel warning on Sunday, suggesting that visitors to Spain over the holiday season should be wary of moving vehicles, tourist areas and transport hubs, as "terrorists may attack with little or no warning."
#Spain: Exercise heightened caution around areas of vehicle movement, including buses, in the Las Ramblas area of Barcelona during Christmas and New Year’s. Terrorists may attack with little or no warning, targeting tourist locations, transportation hubs, and other public areas.
US travel services' advisory level for Spain stands at two out of four, just below "Reconsider travel".
Barcelona and nearby Cambrils were the scenes of two van-ramming attacks in August last year, which killed a total of 16 people and injured over 150. The country's own terror alert has been at level four out of five, or "high", since the January 2015 terrorist attack on the Charlie Hebdo weekly in neighboring France.
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