 Complete the following phrase:  Security bollards are credited with minimizing damage and casualties in the 2007 Glasgow Airport attack, and with preventing ramming in the 2014 Alon Shvut stabbing attack, leading the assailant to abandon his car and attack pedestrians waiting at a bus stop with a knife, after his effort to run them over was thwarted. However, Berlins police chief, Klaus Kandt, argued that bollards would not have prevented the 