Yale University history professor Timothy Snyder on Saturday said that Russian President Vladimir Putin's ruling is "weakening" and noted that preparation for a power struggle is underway.

Snyder pointed in a Twitter thread a sign that Putin is "losing control" is that some former Russian officials such as Dmitry Medvedev spoke about the consequences that await Ukraine and the West.

Medvedev, Putin's staunch ally who served as Russia's former president, recently warned that the West's response to the Russian war in Ukraine could result in the Eastern European country losing "the remnants of state sovereignty and disappear from the world map."

"Usually the news coverage of such pronouncements focuses on their content. It is tempting to get caught up in the Russian fear propaganda. But the real story is that people aside from Putin now feel authorized to make such proclamations. Before the war there was less of this," Snyder said.

He further argued that this "doom propaganda" shows loyalty to Putin while also possibly preparing "for a power struggle after Putin falls."