 Complete the following phrase:  High security bollards are impact-tested in accordance with one or more of three major crash test ratings for vehicle barriers. These are PAS 68 UK, IWA-14 International and ASTM US. Such bollards are used for hostile vehicle mitigation and are designed to protect against potential vehicle borne improvised explosive devices VBIED and vehicle as a weapon VAW attacks such as those seen in the Nice attack in 2016 and the 