Iran's supreme leader released a Holocaust-denial video on Holocaust Remembrance Day

January 27 is Holocaust Remembrance Day, the UN-mandated commemoration of the Nazis' industrial-scale slaughter of 6 million Jews and another 5 million members of various other minority groups during World War II.

But Iranian Supreme Leader Ali Khamenei used the occasion to post an English-subtitled video on his website, which questioned whether the Holocaust happened at all.

The three-minute video is called "Are the Dark Ages Over?" and features audio of a March 2014 speech, during which the Iranian leader claimed, "No one in European countries dares to speak about the Holocaust, while it is not clear whether the core of this matter is reality or not. Even if it is reality, it is not clear how it happened."

The video also showed images of prominent European Holocaust deniers, including British historian David Irving.

Iran's revolutionary regime has included some outspoken deniers and revisionists, to the point at which skepticism or flat-out denial of the historic nature of the Holocaust has often appeared to be an official Iranian-government position.

Former Iranian President Mahmoud Ahmadinejad repeatedly called the genocide a "myth." The regime hosted a revisionism conference in 2006, along with Holocaust-themed cartoon contests in 2006 and 2015.

Iranian President Hassan Rouhani was notably evasive and equivocal in discussing the genocide during a 2013 CNN interview. And in 2006, current Iranian foreign minister Javad Zarif, considered one of the regime's most influential moderates, refused to say whether he personally believed 6 million Jews had been murdered in the Holocaust when the question was directly posed to him during an event at Columbia University.

Earlier this month, most international and US sanctions on Iran were lifted as a result of the July 2015 nuclear deal, a development that paves the way for multibillion-dollar trade deals and even a degree of diplomatic normalization between Iran and Western nations. Rouhani has visited Italy and France this week.

Khamenei's message, however, shows that the thaw has had little impact on some of the least-savory aspects of the regime and its ideology.