Quran says fight those who fight you until PEACE is restored. Self defence to retain and attain peace.
Quran says fight as a last resort after making all efforts for PEACE.
Quran says when fighting this should be proportionate and not overstepping the bounds of justice.
2:216 Fighting in self-defense is ordained for you, even though it is hateful to you. But it may happen that you hate a thing that is good for you, and it may happen that you love a thing that is bad for you. God knows and you know not. [2:190-193, 22:39]
2:193 So, fight them only until there is no more harassment, and Religion may be adopted for the sake of God alone. And if they desist, then let there be no hostility except against those who replace peace with aggression.
[No compulsion or coercion in religion 2:256. Lillah = For the sake of God alone. Zulm = Displace something from its rightful place = Replace good with evil = Oppression = Relegation of the truth = Exploitation = Violation of human rights = Doing wrong to oneself or others = Choosing to do wrong]
4:76 Those who believe fight in the cause of God (against persecution or in self-defense … benign aggression). But the unbelievers fight in the cause of Taaghoot (tyrannical, aggressive forces … malignant aggression). So fight against those friends of the devil. The devil’s strategy is ever weak. [Taaghoot = False gods = Tyrants = Oppressors = Deceptive clergy = Oppressive systems = Those who play god]
9:29 Fight back against those (who keep violating peace treaties and commit aggression 9:1-10) and do not believe in God, nor in the Last Day, nor do they accept what God and His Messenger have made mandatory (being law abiding citizens), nor do they acknowledge the True Religion - among those who were given the scripture, until they pay war reparations in humility. [‘Fight back’ See 9:1-4 Tasreef. Jizyah = War Reparations, Damages to be paid by the aggressors, and not any kind of ‘tribute or tax’ as generally but erroneously translated. 'Mufridaat-e-Raaghib'. The Arabic word for tribute is “Kharaj”. See 18:94 ‘Kharjan’]