The United States already conducts warfare under the norms of centuries of practice of customary international law in areas such as military necessity and proportionality, as well as the norms to which we committed ourselves when we became party to the 1949 Geneva Conventions and the United Nations Charter.
The ATTP then goes on in Paragraphs 1-5 through 1-11 to explain the requirements of the law of armed conflict, the principle of military necessity, the principle of distinction, the principle of proportionality, and the principle of humanity.