Referendums are being held on Friday in four regions of Ukraine controlled by Russia, which world leaders have condemned as a "prelude to illegal annexation".
According to the British news agency Reuters, Ukraine and its allies have made it clear that they will not accept these results.
Voting will continue from Friday to Tuesday in the Ukrainian provinces of Luhansk, Donetsk, Kherson and Zaporizhzhia, which represent about 15 percent of Ukraine's territory.
Russian Foreign Minister Sergei Lavrov said this week that "from the beginning of the operation, we said that the people of the respective regions should decide their own destiny, and the current situation confirms that they want to be the masters of their own destiny." .'
By annexing these four territories to Russia, Moscow can justify the military buildup necessary to defend its territory.
"Occupying Russian territory is a crime that allows you to use all the forces of self-defense," Dmitry Medvedev, Russia's president from 2008 to 2012, said in a post on Telegram.
"If all of this is declared Russian territory, they can declare that it's a direct attack on Russia so they can fight without reservations," Luhansk regional governor Serhii Gedai told Ukrainian TV.
World leaders have condemned the referendum, including US President Joe Biden, UN Secretary-General Antonio Guterres and French President Emmanuel Macron, as well as NATO, the European Union and the Organization for Security and Cooperation in Europe.
On Wednesday, Russian President Putin issued orders to add 300,000 more soldiers to the war.
He had said that if the West shows its "nuclear blackmail" on the conflict, Moscow will respond with the force of all its vast arsenal. If the territorial integrity of our country is threatened, we will use all available means to protect our people.
According to the Russian President, "Russia has many weapons to respond."
Similarly, the Russian President also announced a sudden referendum in the Moscow-occupied areas of Ukraine.
