Recently some UK politicians have been getting milkshakes thrown over them. No injuries resulted, but the question of when violence, including relatively minor acts such as this, can be justified or viewed as acceptable came up again.
What are some political philosophies that include violence as an eventual resort, under some specific circumstances? For example, the US 2nd Amendment seems to suggest that violence against government employees may be justified sometimes, i.e. the "well regulated militia" clause is interpreted by some as the population retaining the option to violently overthrow the government.
Another example would be various anti-fascist groups and white supremacists, but I'm asking about political philosophies so things like conspiracy theories (e.g. the "race war" or "great replacement") are not really on-topic.