While Moscow still claims the troops who have taken control of much of Crimea are local self-defense forces, their activities have drawn comparisons with Nazi Germany's occupation of Poland and Czechoslovakia, and with the U.S. invasion of Iraq and Afghanistan. Several experts disagree, however, on whether those comparisons are accurate.
Is Russian President Vladimir Putin behaving like Adolf Hitler?
Former U.S. Secretary of State Hillary Clinton recently suggested that Putin's claim that Russia must protect Russian minorities in Ukraine was similar to statements Hitler had made in the 1930's.
" ... when Germany under the Nazis kept talking about how they had to protect German minorities in Poland and Czechoslovakia and elsewhere throughout Europe," said Clinton.
That comparison resonates strongly in Central Europe, according to Atlantic Council senior fellow Jorge Benitez.
"Because at that time, the international community issued just diplomatic condemnations but didn't stand up to protect the integrity and the territory of Czechoslovakia," he said. "So there's very much a lot of pressure on the international community to see, 'How will they respond to Russia's use of force to seize Ukrainian territory in Crimea?'."
Georgetown University professor Anthony Clark Arend mostly agrees, but cautions against comparing any modern leader with Hitler.
"If we accept the fact that, okay, he's like Hitler, then it's going to say to us that we have to respond as we responded to Hitler. We have to act as we acted in World War II, and that's not the case here," said Arend.
According to James Goldgeier, Dean of the School of International Service at Washington's American University, the closest parallels with the situation in Ukraine are Russia's previous military actions in Moldova and Georgia. He said the Russians have removed a part of Ukraine's territory from the control of the central government in Kyiv.
"And this is a highly destabilizing situation for Ukraine, and it makes it difficult for Ukraine to pursue a pro-Western course, just as their actions in Georgia and Moldova have made it difficult for those countries," said Goldgeier.
Georgetown's Arend believes Putin was more concerned with what he saw as unrest on his border. "I don't think that Putin wanted any of this. I don't think that he wanted to destabilize Ukraine. I think, rather, he saw things moving in a way, and felt, 'we gotta act before things get worse.'"
Another possible parallel in Ukraine is with the U.S. invasion of Iraq in 2003. Arend contends that also was a violation of international law.
"It was not authorized by the Security Council. The action was not taken in response to either an existing threat or a potential threat against the United States," said Arend.
Benitez said, however, there is a difference. "The United States went in there to remove a regime that was building weapons of mass destruction that the international community believed were there and were going to be used to harm. This is just a blatant power play in the Crimea by the Russian government to seize the territory of another country."
The ultimate resolution of the Ukraine situation will determine how it's seen by history.