Editing Ultra (cryptography) (section)

===Holocaust intelligence===
Historians and [[Holocaust studies|Holocaust researchers]] have tried to establish when the Allies realized the full extent of Nazi-era extermination of Jews, and specifically, the extermination-camp system. In 1999, the U.S. Government passed the Nazi War Crimes Disclosure Act ([[Act of Congress|P.L.]] 105-246), making it policy to declassify all Nazi war crime documents in their files; this was later amended to include the Japanese Imperial Government.<ref>{{Cite web |url=http://thomas.loc.gov/cgi-bin/cpquery/?&dbname=cp106&sid=cp106uUzJ1&refer=&r_n=hr969.106&item=&&&sel=TOC_161095& |title=Nazi War Crimes and Japanese Imperial Government Disclosure Act of 2000 |access-date=8 September 2015 |archive-date=3 February 2016 |archive-url=https://web.archive.org/web/20160203010047/http://thomas.loc.gov/cgi-bin/cpquery/?&dbname=cp106&sid=cp106uUzJ1&refer=&r_n=hr969.106&item=&&&sel=TOC_161095& |url-status=dead }}</ref> As a result, more than 600 decrypts and translations of intercepted messages were disclosed; [[National Security Administration|NSA]] historian Robert Hanyok would conclude that Allied communications intelligence, "by itself, could not have provided an early warning to Allied leaders regarding the nature and scope of the Holocaust."<ref>{{Harvnb|Hanyok|2004|p=126}}</ref>

Following [[Operation Barbarossa]], decrypts in August 1941 alerted British authorities to the many massacres in occupied zones of the [[Soviet Union]], including those of Jews, but specifics were not made public for security reasons.<ref>{{cite web|url=http://www.jewishgen.org/yizkor/poland/pol001.html|title=Poland and her Jews 1941 - 1944|website=www.jewishgen.org}}</ref>  Revelations about the concentration camps were gleaned from other sources, and were publicly reported by the [[Polish government-in-exile]], [[Jan Karski]] and the [[World Jewish Congress|WJC]] offices in Switzerland a year or more later.<ref>See: [[Riegner Telegram]]</ref> A decrypted message referring to "[[Einsatz Reinhard]]" (the [[Höfle telegram]]), from 11 January 1943 may have outlined the system and listed the number of Jews and others gassed at four death camps the previous year, but codebreakers did not understand the meaning of the message.<ref>{{Harvnb|Hanyok|2004|p=124}}</ref> In summer 1944, [[Arthur M. Schlesinger Jr.|Arthur Schlesinger]], an [[Office of Strategic Services|OSS]] analyst, interpreted the intelligence as an "incremental increase in persecution rather than&nbsp;... extermination".<ref>{{Harvnb|Schlesinger|1992|pp=66–67}}</ref>