Siege (sometimes stylised as SIEGE), originally published as Siege: The Collected Writings of James Mason, is an anthology of essays by the neo-Nazi James Mason. After growing disillusioned with the mass movement approach of neo-Nazi movements, Mason began advocating for white revolution through terrorism. Mason originally wrote the essays from 1980 to 1986 for the National Socialist Liberation Front newsletter of the same name, which was itself the revival of a 1970s periodical created by Joseph Tommasi. The essays were published and edited in a single volume by Michael J. Moynihan in 1992. It has since been republished and reedited multiple times.

Though the book was reviewed in several periodicals upon its release and was praised and distributed by the influential white supremacist Tom Metzger, most neo-Nazis of the time either ignored or criticized the book. It was not influential for many years, though was occasionally discussed in academic literature. In the 2010s the book found a new audience online among younger neo-Nazis due to the book's republication by the neo-fascist forum Iron March. In addition to its promotion of neo-Nazism, it lionizes serial killers, mass murderers, and Charles Manson. Siege advocates neo-Nazi lone wolf terrorism, and has been tied to numerous terrorist groups.

James Mason (born 1952) had been a neo-Nazi since he was 14, initially joining George Lincoln Rockwell's American Nazi Party (by then renamed the National Socialist White People's Party), before he joined a militant splinter of that group, the National Socialist Liberation Front (NSLF). Siege emerged out of the faction of the NSWPP that wished for explicit revolutionary violence. Another former member of this wing of the ANP was William Luther Pierce, who wrote The Turner Diaries.

The NSLF was launched by Joseph Tommasi in 1974, after he was kicked out of the NSWPP. While James Mason did not initially follow Tommasi in leaving the NSWPP, he grew increasingly dissatisfied with it, and observed Tommasi's group with interest. He later left the NSWPP some time after. The NSLF took credit for several bombings, arsons, and shootings.

One of the NSLF's periodicals was named Siege, created by Tommasi. The origin of the name of the original Siege periodical is disputed; Mason claimed Tommasi took the name from a book about the Weather Underground. However, there is no book by this name about the Weather Underground. Spencer Sunshine proposed that Tommasi had actually taken the title from the book Miami and the Siege of Chicago by Norman Mailer, which discussed a conflict between the Weather Underground's predecessor group and the police. Tommasi was murdered by a member of the NSWPP in 1975, and was treated as a martyr by the NSLF.

When he joined the NSLF, Mason became the editor of a revival of the original Siege. The Siege newsletter ran each month from August 1980 until June 1986. Each issue was six pages and was almost always written by Mason. Mason's writings frequently built off the ideologies of George Lincoln Rockwell, Joseph Tommasi, Adolf Hitler, and William Luther Pierce. The newsletter also sometimes came in the form of reprints and writing by Joseph Tommasi, Perry Warthan, and Frank Spisak.

During this time, Mason's neo-Nazi ideology remained ardent, but also fluctuated. For example, he ultimately proclaimed Christianity as an important facet of neo-Nazism in the last years of the publication. Another fluctuation during this newsletter was his support for violent activism. In the beginning, Mason wrote fondly of violent tactics from leftists and black nationalists. Later, however, his support for this sort of activism — even more broadly — waned. Through and through, the SIEGE Newsletter remained anti-system, even rejecting notions of being conservative or right-wing. It advocated "a TOTAL WAR" and advocated acts that would end in a "total and complete revolution" against the establishment, what it called "the Jew-Capitalist System!!" While writing Siege, he became increasingly disillusioned by neo-Nazi group organization, and in favor of self-directed action; he initially promoted open guerrilla warfare but came to see this as insufficient.

In terms of violent activism, Mason was drawn to state and civilian clashes such as the 1981 Brink's robbery and the 1985 MOVE bombing. However, he advised that the neo-Nazis should let black nationalists and leftists fight this fight with the state and that the neo-Nazi movement should deactivate any violent activism. The newsletter ended when Mason received harsh criticism over his views from other neo-Nazis for his support of Charles Manson. During its run, the newsletter had a circulation of less than 100 copies.