Increasingly, the public is beginning to see a trend towards terrorist attacks targeting crowded, so-called soft targets. The Australian government, in a public paper discussing terrorism in crowded spaces, noted that terrorist prefer such places because density increases the likelihood of large numbers of casualties, many crowded places are accessible, the psychological effect on the public, and the attention such attacks garner. These were seen with the attacks that have occurred over the last few years in United Kingdom such as the London Bridge attack, the Manchester concern bombing, and the Borough Market attack; elsewhere in Europe, there were attacks in France on Bastille Day in 2016 and an attack at a Berlin Christmas market; in the United States, it is seen in the mass shootings that have occurred in schools, nightclubs, concerts, and at mass public events (e.g., the Boston Marathon bombing). Inherent in public spaces – especially crowded and non-permanent spaces – are significant security challenges that authorities and planners must contend with as they seek to reduce both the risk of terrorist attacks and, if an attack were to occur, its damage. Some common targets that concern authorities are malls, stadiums, and shopping centers.