Launched as the National Guardian in October 1948 by James Aronson, Cedric Belfrage  John McManus, its contributors included pro-Communist writers such as Agnes Smedley and Anna Louise Strong. Wilfred Burchett was also a significant influence in the National Guardian's editorial policies. Testimony by Elizabeth Bentley and confirmed by the Venona intercepts, revealed that Belfrage made contact with Soviet espionage agents during World War II. In 1947 the FBI questioned Belfrage, who admitted to having provided confidential information to the Soviets.
Progressives for Obama webmaster Carl Davidson was a regular pro-Maoist contributor in the 1970s as was Wikipedia "expert" Chip Berlet in the 1980s. The publication has been regularly cited as an extremist publication in John George and Laird Wilcox's Nazis, Communists, Klansmen, and Others on the Fringe: Political Extremism in America.
Korean War disinformation
Burchett is most famous for his false reports on American use of germ warfare in the Korean War and his collaboration in the brainwashing of American POWs. In June 1952 over Beijing radio Burchett accused the Americans of perpetrating "the most monstrous crimes against humanity." He said that in germ warfare the Americans had launched upon mankind a weapon more frightful than the atomic bomb. In order to support these allegations, Burchett assisted in the extraction of "confessions" from American pilot POWs.
The hoax of American use of germ warfare in Korea has persisted among Marxist-Leninist writers. In 1998, however, news reports noted:
- "...documents from Russia's Presidential Archive finally prove, more than four decades after the fact, that the United States was the victim of a disinformation campaign scripted by North Korea, China, and the Soviet Union.
- "False plague regions were created, burials...were organized" measures were taken to receive the plague and cholerabacillus.
Hiss, the Rosenbergs, and McCarthy
The National Guardian drew its readership largely from the Progressive Party. The first issue featured an article by progressive Henry Wallace, whom the National Guardian endorsed as a presidential candidate on the independent ballot that year. The paper also found support in the American Labor Party. Congressman Vito Marcantonio was especially enthusiastic about the paper. It reported on such issues and events as the trial and execution of Ethel and Julius Rosenberg, charged with atomic espionage for the Soviet Union. The National Guardian also was took up the causes of Alger Hiss, Corliss Lamont, and Ann and Carl Braden. 
In 1953 Aronson and Belfrage were subpoenaed to testify before the Senate Permanent Subcommittee on Investigations chaired by Sen. Joseph McCarthy of Wisconsin. The National Guardian declared the investigation
- "a move to persecute and if possible intimidate the editors of an independent news-weekly, which has opposed the policies of war, repression and plunder of the Eisenhower Administration and the previous bi-partisan administration of President Truman.
Aronson later asserted "we were not Communists, but...we felt it was our right--our duty--to remain silent before a committee of Congress which we felt had no authority to inquire into our beliefs and associations." Aronson described the National Guardian as "an independent and independently-owned newsweekly which took strong issue with basic governmental policy, foreign and domestic," and he denied that it adhered to an "international Communist conspiracy." Aronson and Belfrage explained that they invoked their Fifth rather than First Amendment rights at the advice of their attorney. "Our lawyer had reasoned in a four-hour argument that if we invoked the First we would almost surely be cited for contempt, be convicted, and, in the existing climate, go to prison. He said the National Guardian would suffer and perhaps even be forced to suspend publication if its two chief editors were jailed." 
Following their testimony at a public hearings on May 14, 1953 , Cedric Belfrage was arrested on a deportation warrant and held on Ellis Island until he was released on bond on June 10. He was ordered deported on December 9, 1954. After losing his appeal, he was again arrested in May 1955 and deported to Great Britain in August 1955.
Aronson continued to publish the National Guardian until 1967, when he resigned. The papers masthead was changed from "progressive" to "radical" newsweekly and later the name was changed to simply Guardian.
An appreciation of Ho Chi Minh
The National Guardian was one of the first American based newspapers that supported Soviet foreign policy oppossition to the Vietnam War and carried on-scene reports from Wilfred Burchett.  In a secret White House meeting with President Johnson in 1967 Burchett is referred to as "often a reliable spokesman for North Vietnam". 
In the late 1960s the Guardian develops stronger links with Students for a Democratic Society (SDS) and the Student Non-Violent Coordinating Committee (SNCC) and other leftist radicals. By the end of 1969 its paid readership was 24,000, the highest since the aftermath of the Wallace campaign in 1948. 
Throughout the 1950s, 60s, 70s, and 80s, the paper supported so-called "national liberation struggles", Africa in the 1950's, Southeast Asia in the 1960's and early 1970's, and Latin America in the 1980's.
Break with Maoists
In 1975 a break between the Maoist October League (OL) and the Guardian led to bitter private meetings and internal staff struggles. An exchange of public polemics on foreign policy and the International Women’s Day actions/”no united action with revisionists” line finally prompted the OL to pulls its cadre out of the staff. Renee Blakkan, Martin Nicolaus, Nancy Nikcevich and Rod Such resigned; Carl Davidson was also associated with the OL position but did not resign at this time.
By the 1980s as it became more and more obvious even to Marxists that Marxism-Leninism was failing, and Marxist class struggle was a hard sell, the Guardian reinvented itself along with other elements of the American left and shifted to issues of ethnicity and gender and a kind of Marxism-Leninism of race and sex emerged, complete with a special vocabulary of clichés', buzzwords and slogans. Epitomized by a new knee-jerk rhapsodizing about the radical feminist, gay rights and anti-racist movement. In the 1980s they took on a new intensity and significance. Radical antiracist, gay, and feminist cadres with Marxist-Leninist tendencies found a congenial home in the new Guardian. 
- Chip Berlet and Jean Hardisty, An Anatomy of the New Right, Guardian Special Report (Fall, 1981).
- Chip Berlet Right-wing conspiracists make inroads into left, The Guardian, September 11, 1991, page 3.
- Ken Lawrence, Fulani: Heir to an Ugly Party History, The Guardian, October 26, 1988. 
- FBI Silvermaster file, Vol. 55, pgs. 35 - 39, Cedric Belfrage, James Aronson, and Ilya Ehrenberg.
- Carl Davidson, LinkedIn.com, retrieved March 13, 2010.
- Left in Form, Right in Essence: A Critique of Contemporary Trotskyism, Carl Davidson, (1973). This pamphlet was originally published as a series of 12 articles in early 1973 in the Guardian newsweekly. Second printing Spring 1974. Retrieved from 对当代托洛茨基主义的批判：英文论集百花齐放 - 中国文革研究网, March 15, 2010.
- Nazis, Communists, Klansmen, and Others on the Fringe: Political Extremism in America,]John George and Laird Wilcox, Prometheus Books, Buffalo, New York, 1992, Chapter 9, Guardian, pgs. 125-131. (ISBN 0-87975-680-2)
- Bruce B. Auster, Unmasking An Old Lie: A Korean War Charge Is Exposed As a Hoax, U. S. News & World Report (16 November 1998), p. 52.
- Tamiment Library/Robert F. Wagner Labor Archives, Guide to the Cedric Belfrage Papers 1922-1990.
- James Aronson, The Press and the Cold War (Boston: Beacon Press, 1970).
- Executive Sessions of the Senate Permanent Subcommittee on Investigations, Vol. 2, Eighty-third Congress, 14 May 1953, pgs. 1135-1164.
- HO CHI MINH an appreciation by Wilfred Burchett
- U.S. Department of State, Foreign Relations, 1964-1968, Volume V, Vietnam 1967, Released by the Office of the Historian, Document 364.
- Chronology of Political Events, Part Two, 1967-1970, Revolution In The Air: Sixties Radicals Turn to Lenin, Mao and Che, Max Elbaum.
- Chronology of Political Events, Part Four 1975-1980, Max Elbaum. Retrieved from March 18, 2010.
- John George and Laird Wilcox, Nazis, Communists, Klansmen, and Others on the Fringe: Political Extremism in America, Prometheus Books, Buffalo, New York, 1992, (ISBN 0-87975-680-2), pgs. 125-131.