“What business is it of ours whether Russia or Germany or England or France or Italy or Austria live under democracies or monarchies? Whether they are Fascists or Communists? Our problem is to preserve our own democracy. And very little, if anything, has been accomplished to assure us that the World War was really the war to end all wars.”

Glimpses of World History (1949)

From interview with Vreme, May 24, 1993
Interviews (1993 – 1995)

30 July, 1924, quoted in World War I: The Definitive Visual History (United States: Smithsonian, 2014), p. 20
1920s

Waldersee in his diary, 15 October 1885, quoted in Scott A. Silverstone, From Hitler's Germany to Saddam's Iraq

Published as having been made in an (August 1936) interview http://www.greatwar.nl/frames/default-churchill.html with William Griffin, editor of the New York Enquirer http://en.wikipedia.org/wiki/National_Enquirer, who was indicted for sedition http://www.time.com/time/magazine/printout/0,8816,773366,00.html by F.D.R.'s http://www.whitehouse.gov/history/presidents/fr32.html Attorney General Francis Biddle http://www.usdoj.gov/osg/aboutosg/biddlebio.htm in 1942. In a sworn statement before Congress in 1939 Griffin affirmed Churchill had said this; Congressional Record (1939-10-21), vol. 84, p. 686. In 1942, Churchill admitted having had the 1936 interview but disavowed having made the statement (The New York Times, 1942-10-22, p. 13).
In his article "The Hidden Tyranny," Benjamin Freedman attributed this quotation to an article in the isolationist http://www.time.com/time/magazine/article/0,9171,795133,00.html publication Scribner's Commentator in 1936. However, that magazine did not exist until 1939. He may have gotten the date wrong or might have been referring to one of its predecessors, Scribner's Monthly http://cdl.library.cornell.edu/moa/browse.journals/scmo.html or Payson Publishing's The Commentator http://www.time.com/time/magazine/article/0,9171,765655,00.html.
Disputed

Marx-Engels Gesamt-Ausgabe, Erste Abteilung, Volume 7, March to December 1848, p. 304. Leopold Schwartzschild, Karl Marx: The Red Prussian, New York: NY, The Universal Library, Grosset & Dunlap, 1947, p. 202

There Will Be No Reconciliation with America before Withdrawal, Apology, and Compensation http://www.memritv.org/Transcript.asp?P1=1402, exclusive interview, March 2007.
Targeting collaborators

Source: Fight Club

What I Didn't Find in Africa (2003)
Context: I was convinced before the war that the threat of weapons of mass destruction in the hands of Saddam Hussein required a vigorous and sustained international response to disarm him. Iraq possessed and had used chemical weapons; it had an active biological weapons program and quite possibly a nuclear research program — all of which were in violation of United Nations resolutions. Having encountered Mr. Hussein and his thugs in the run-up to the Persian Gulf war of 1991, I was only too aware of the dangers he posed.
But were these dangers the same ones the administration told us about? We have to find out. America's foreign policy depends on the sanctity of its information. For this reason, questioning the selective use of intelligence to justify the war in Iraq is neither idle sniping nor "revisionist history," as Mr. Bush has suggested. The act of war is the last option of a democracy, taken when there is a grave threat to our national security. More than 200 American soldiers have lost their lives in Iraq already. We have a duty to ensure that their sacrifice came for the right reasons.