I'm quoting from my other answermy other answer to support this.
Protection of arahats (DN 16):
"What have you heard, Ananda: do the Vajjis duly protect and guard the arahats, so that those who have not come to the realm yet might do so, and those who have already come might live there in peace?"
"I have heard, Lord, that they do."
"So long, Ananda, as this is the case, the growth of the Vajjis is to be expected, not their decline."
I'm not sure whether Buddha, The Gospel (Paul Carus, 1894) is based on canonical texts:
Simha continued: "I am a soldier, O Blessed One, and am appointed by the king to enforce his laws and to wage his wars. Does the Tathagata who teaches kindness without end and compassion with all sufferers, permit the punishment of the criminal? and further, does the Tathagata declare that it is wrong to go to war for the protection of our homes, our wives, our children, and our property? Does the Tathagata teach the doctrine of a complete self-surrender, so that I should suffer the evil-doer to do what he pleases and yield submissively to him who threatens to take by violence what is my own? Does the Tathagata maintain that all strife, including such warfare as is waged for a righteous cause should be forbidden?"
The Buddha replied: "He who deserves punishment must be punished, and he who is worthy of favor must be favored. Yet at the same time he teaches to do no injury to any living being but to be full of love and kindness. These injunctions are not contradictory, for whosoever must be punished for the crimes which he has committed, suffers his injury not through the ill-will of the judge but on account of his evildoing. His own acts have brought upon him the injury that the executer of the law inflicts. When a magistrate punishes, let him not harbor hatred in his breast, yet a murderer, when put to death, should consider that this is the fruit of his own act. As soon as he will understand that the punishment will purify his soul, he will no longer lament his fate but rejoice at it."
The Blessed One continued: "The Tathagata teaches that all warfare in which man tries to slay his brother is lamentable, but he does not teach that those who go to war in a righteous cause after having exhausted all means to preserve the peace are blameworthy. He must be blamed who is the cause of war. The Tathagata teaches a complete surrender of self, but he does not teach a surrender of anything to those powers that are evil, be they men or gods or the elements of nature. Struggle must be, for all life is a struggle of some kind. But he that struggles should look to it lest he struggle in the interest of self against truth and righteousness.
