US Dept of State Issues Terror Caution

"...Extremists may elect to use conventional or non-conventional weapons, and target both official and private interests. 

Examples of such targets include high-profile sporting events, residential areas, business offices, hotels, clubs, restaurants, places of worship, schools, public areas, shopping malls, and other tourist destinations both in the United States and abroad where U.S. citizens gather in large numbers, including during holidays."

http://www.travel.state.gov/travel/cis_pa_tw/pa/pa_4787.html