The contribution discusses the general problems armed groups face when they want to respect, as they must, international humanitarian law (IHL) and specific difficulties in the field of the conduct of hostilities : whether the police and government officials may be targeted; how the proportionality of an attack aiming at symbolic political advantages can be assessed; how they can accept the surrender of government soldiers and then detain them; or the feasibility of precautionary measures when the group has only one weapon that is capable of reaching the enemy. The author however recalls that the rules of IHL are flexible and the obligations are situation-dependent. Therefore most rules are capable of being respected by an armed group, if interpreted taking the peculiarities of armed groups into account.