Since the beginning of the nineties Germany has taken part in UN military missions. The Afghanistan mission since 2001 is the largest and most visible German engagement at present. Foreign assignments of German soldiers do not only pose questions with regard to constitutional law but might also have legal bearings on criminal law. When soldiers cause death of enemy combatants or civilians the question of individual criminal responsibility of the operating soldier and commander in charge arises. The wider context of international law in which military missions take place brings the relation between national criminal law and international law into focus.In its first part this article deals with criminal responsibility under the Völkerstrafgesetzbuch of 2006. It has been included into German law in the aftermath of issuing the Rome Statute of the International Criminal Code and comprehends the statutory offence of genocide, crimes against humanity and war crimes. War crimes may only be committed during an armed conflict, requiring an examination of the conditions under which a conflict might be qualified as an international or non-international armed conflict. In the following, the authors focus on the highly relevant war crime of disproportionally causing death of civilians. Especially with regard to the more complicated situation of a non-international armed conflict a careful determination of who falls in the category of a civilian is undertaken.The second part analyses a parallel application of the German Criminal Code and the Völkerstrafgesetzbuch. As this question is answered in the affirmative, causing loss of life of a person during a military mission fulfills the actus reus of homicide. However, the fact that the act takes place within a military mission is to be taken into account also within the German Criminal Code. While compliance with internal Bundeswehr or NATO rules may not exculpate the soldier, compliance with international humanitarian law leads to exemption from punishment. The rules of international humanitarian law apply to international and non-international armed conflicts and are congruent with regard to the basic principles. An act of a soldier may not be punishable to the extent that the soldier acted in conformity with the applicable rules of international humanitarian law. In the view of the authors this is especially important with regard to the rules of procedure as a violation thereof is not reflected as a crime in the Völkerstrafgesetzbuch.In cases in which soldiers act outside the context of an armed conflict, international humanitarian law is not applicable. It is argued that in these situations the human rights laws' general prohibition to use deadly force outside the narrow boundaries of self-defense persists. A UN mandate, even in conjunction with a mandate of the German Bundestag, by itself cannot be construed as to exculpate an individual soldier as the mandate concerns the aspect of ius ad bellum and not ius in bello and has no bearing on the individual.With regard to the mens rea a soldier might act without intent, leading to a conviction for negligence.In sum, the authors illustrate that international law presents precise standards for legitimate and illegitimate operations in armed conflicts. From this it follows whether a soldier who causes the death of another person has committed a crime and is to be tried in a German Court proceeding or not.