Pacifism is the belief that disputes between nations can and should be settled peacefully. It is the opposition to war and the use of violence as a means of settling disputes. It can include the refusal to participate in military action.
Antimilitarism does not reject war in all circumstances, but rejects the belief or desire to maintain a large and strong military organization in aggressive preparedness for war.
Anarcho-syndicalist Georges Sorel advocated the use of violence as a form of direct action, calling it "revolutionary violence", which he opposed in Reflections on Violence (1908) to the violence inherent in class struggle. Similarities are seen between Sorel and the International Workingmens' Association (IWA) theorization of propaganda of the deed.
Walter Benjamin, in his Critique of Violence (1920) demarcates a difference between "violence that founds the law", and "violence that conserves the law", on one hand, and on the other hand, a "divine violence" that breaks the "magic circle" between both types of "state violence". What distinguishes these two kinds of violence fundamentally is their mode of operation; whereas law-establishing and law-preserving violence operate instrumentally on a continuum of means and ends, wherein the means of physical violence justify the political-juridical ends of the law, the Benjaminian concept of 'divine violence' is unique insofar as it is a bloodless violence 'of pure means' through which the law itself is destroyed. The example Benjamin provides in his essay is that of a the General Strike, the latter of which is a key element of Sorel's Reflections on Violence (cited in this essay by Benjamin). The "violence that conserves the law" is roughly equivalent to the state's monopoly of legitimate violence. The "violence that founds the law" is the original violence necessary to the creation of a state. "Revolutionary violence" removes itself from the sphere of the law by shattering its instrumental logic of violence (i.e. its deployment of violence as a means of instituting, preserving and enforcing its own authority). 
Giorgio Agamben showed the theoretical link between the law and violence permitted Nazi-thinker Carl Schmitt to justify the "state of exception" as the characteristic of sovereignty. Thus indefinite suspension of the law may only be blocked by breaking this link between violence and right.
Henry David Thoreau's 1849 essay "Civil Disobedience" (see text), originally titled "Resistance to Civil Government", can be considered an antimilitarist point of view. His refusal to pay taxes is justified as an act of protest against slavery and against the Mexican–American War, in accordance to the practice of civil disobedience. (1846–48). He writes in his essay that the individual is not with obligations to the majority of the State. Instead the individual should "break the law" if the law is "of such a nature that it requires you to be the agent of injustice to another."
Capitalism has often been thought by antimilitarist literature to be a major cause of wars, an influence which has been theorized by Vladimir Lenin and Rosa Luxemburg under the name of "imperialism". The military-industrial complex has been accused of "pushing for war" in pursuit of private economic or financial interests.