Only as a general orientation in the various topics, the following textbook is indicated a valid starting point:
Duncan Bell (ed.), Ethics and World Politics, Oxford University Press, 2010.
Patrick Hayden (ed.), Ethics and International Relations, Routledge, 2013.
Niger Dower, The Ethics of War and Peace, Polity, 2009.
Uwe Steinhoff, On the Ethics of War and Terrorism, Oxford University Press, 2007