In a statement it said, “Recent armed attacks targeting foreign nationals in Saudi Arabia that resulted in many deaths and injuries, including US citizens, appear to have been preceded by extensive surveillance.”

“Extremists may be surveying Westerners, particularly at hotels and those using rental cars and US contractors may be some of the potential targets. Our indictment of key Hamas figures may also be used as an excuse to target American citizens or American interests throughout the region,” it added.