There may be situations in the theatre of operations leading to normative interactions between rules applicable to the protection of foreign investments. During armed conflict, foreign investment may be protected by applicable investment treaty but may at the same time qualify as military objective. This chapter therefore summarizes how selected rules of investment law, international humanitarian law and international human rights law interact in the new context of protection of foreign investments during hostilities. It then presents methodology to tackle these interactions and applies it to the identified interactions or conflicts of norms (including the question of the position and function of the popular lex specialis principle). As part of it, this chapter demonstrates how the notion of military necessity may inform the interpretation of international investment law standards (namely compensation for losses or non-precluded measures clauses).