Since the events of September 11, 2001, the possibility of an intentional act targeting the chemical process industry has become realistic. It is, therefore, a great concern to be able to predict the immediate consequences of such an act. This study is intended to improve our knowledge about the sequence of events that occurs when a high-speed bullet (> 1000 m s(-1)) penetrates a vessel filled with toxic liquid. We find that, prior to liquid ejection, several well-defined phases occur, including the phenomenon known as the "hydraulic ram." This paper focuses on projectile-target interactions and explains how the decay of projectile velocity is related to the initial conditions of the target. (c) 2008 Elsevier Ltd. All rights reserved.