Hazardous substances such as unexploded ordnance represent a serious threat. It is necessary to develop new methods and equipment for their elimination. For this reason, a laser ablation process is developed where the shell of the objects are weakened in a defined manner to reduce the threat to the environment. This article shows how 25 mm thick steel sheets can be weakened with ablation rates of more than 3000 mm³/min and achieved ablation depths of more than 15 mm by means of an adapted process strategy and an off-axis process gas control. Despite the high incoming process energy, it is ensured that there is no danger to affect the hazardous substances. A critical temperature of 300 °C is not exceeded at the rear surface of the sheet metal.