The Romans had various ways of justifying their imperial aims and methods, some high-minded, some less so. We find in particular that they could give honourable and satisfying explanations of their aims and methods in war. Here for example is Cicero:
quare suscipienda quidem bella sunt ob earn causam, ut sine iniuria in pace uiuatur; parta autem uictoria conseruandi ii, qui non crudeles in bello, non immanes fuerunt, ut maiores nostri Tusculanos, Aequos…in ciuitatem etiam acceperunt, at Carthaginem…funditus sustulerunt…mea quidem sententia paci, quae nihil habitura sit insidiarum, semper est consulendum. et cum iis, quos ui deuiceris, consulendum est, tum ii qui armis positis and imperatorum fidem confugient, quamuis murum aries percusserit, recipiendi (Off. 1. 35).