Much like Russia after the fall of the Soviet Union, Germany was bitter about losing territory when the map of Europe was redrawn after World War I. After annexing Austria in 1938, Hitler turned his attention to the three million Germans who ended up living in a region of Czechoslovakia known as Sudetenland. Falsely claiming that hundreds had been killed, Hitler massed troops on the Czech border, demanding the region be reunited with the “German homeland.” European leaders acquiesced, Hitler pledged no further aggression, and the German army moved in.

With Russian troops approaching Ukraine’s capital Thursday, the country’s official Twitter account posted a Putin-Hitler meme, above. But historical comparisons to Hitler are problematic. In 2014, when Russian troops moved into Ukraine’s Crimea region, critics from Prince Charles to Hillary Clinton faced blowback for comparing Putin to Hitler, a genocidal madman who oversaw the extermination of six million Jews and millions of others.

In Putin’s own words, “To have a better understanding of the present and look into the future, we need to turn to history.” In 2014, many believed that his aggression would be limited to Crimea. The all-out assault on Ukraine, some say, reveals Putin’s “imperialist” ambitions. In a rambling speech this week, he waxed nostalgic for the former Soviet Union and the Russian empire, and challenged the idea that Ukraine was a real nation, saying it consists largely of “the lands of historical Russia.”

Putin claims the invading Russian army will not occupy Ukraine forever, but it remains to be seen if this attack will become a wider war. He has warned that “anyone who tries to interfere with us” will suffer “consequences you have never faced in your history.”

IREM OZTURAN, an intern at Retro Report, is a journalism and economics student at Northwestern. KAREN M. SUGHRUE is a Retro Report senior producer. This article first appeared in Retro Report’s free weekly newsletter. Subscribe and receive lessons from history in your mailbox. Follow us on Twitter @RetroReport.