A good country does not begin a war except to defend its honor or to protect itself. ... Wars are unjust if they are undertaken without cause. Only a… - Cicero

Those wars are unjust which are undertaken without provocation. For only a war waged for revenge or defense can be just.

Est quidem vera lex recta ratio naturae congruens, diffusa in omnes, constans, sempiterna, quae vocet ad officium iubendo, vetando a fraude deterreat; quae tamen neque probos frustra iubet aut vetat nec improbos iubendo aut vetando movet. Huic legi nec obrogari fas est neque derogari ex hac aliquid licet neque tota abrogari potest, nec vero aut per senatum aut per populum solvi hac lege possumus, neque est quaerendus explanator aut interpres eius alius, nec erit alia lex Romae, alia Athenis, alia nunc, alia posthac, sed et omnes gentes et omni tempore una lex et sempiterna et immutabilis continebit, unusque erit communis quasi magister et imperator omnium deus, ille legis huius inventor, disceptator, lator; cui qui non parebit, ipse se fugiet ac naturam hominis aspernatus hoc ipso luet maximas poenas, etiamsi cetera supplicia, quae putantur, effugerit.

What! You would convict me from my own words, and bring against me what I had said or written elsewhere. You may act in that manner with those who dispute by established rules. We live from hand to mouth, and say anything that strikes our mind with probability, so that we are the only people who are really at liberty."

Quamquam scripsit artem rhetorieam Cleanthes, Chrysippus etiam, sed sic, ut si quis obmutescere concupierit, nihil aliud legere debeat.