Moscow, Russia - Russian President Vladimir Putin has signed a decree ordering the partial mobilization of Russia's armed forces, set to begin later on Wednesday.

In a major televised address, he also warned other states not to attack Russian territory.

"If the territorial integrity of our country is threatened, we will absolutely use all available means to protect Russia and our people. This is not a bluff."

At the same time, Putin warned against "blackmailing" Russia with nuclear weapons. "Those who try to blackmail us with nuclear weapons should know that the compass needle can turn in their direction," he said.

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"It is in our historical tradition, in the destiny of our people to stop those who seek world domination, who threaten our motherland, our homeland with dismemberment and oppression," Putin said.

Russia's nuclear weapons have been put on combat readiness in the wake of the war in Ukraine.

The partial mobilization of Russian forces is also meant to solve personnel problems at the front, with the number of reservists being drafted at 300,000, according to Defense Minister Sergei Shoigu. In total, there are 25 million reservists available.

At the same time, Putin announced that he would support the "referendums" in the occupied territories of Ukraine on joining Russia.

Moscow-backed separatists announced plans to conduct these referendums in the occupied regions of Luhansk, Donetsk, Kherson, and Zaporizhzhia. The move triggered fierce condemnation from the international community.

"We support the decision made by the majority of citizens in the people's republics of Luhansk and Donetsk, in the Kherson and Zaporizhzhia regions," Putin said.

The simultaneous referendums are to start Friday and end on Tuesday. They are considered a reaction to the current Ukrainian counteroffensive in the east of the country, where Ukrainian forces continued a spate of recent successes, taking back territory occupied by Russia since its invasion of Ukraine began at the end of February.

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Russia annexed the Ukrainian Black Sea peninsula of Crimea in a similar way in 2014. The vote was not recognized internationally and the same reaction is expected this time around.

Russian political scientist Tatyana Stanovaya said that Putin had decided to stage the referendums after his original plans to quickly seize the territories in Ukraine failed.

After taking over the regions, she said, Putin would have the option of defending the territories under threat of using nuclear weapons. This, Stanovaya thinks, means he has significantly raised his stakes in the war.

Meanwhile, the Ukrainian leadership in Kyiv has warned citizens against voting in the referendums.

"Any participation in the 'referendums' will be considered a violation of Ukraine's territorial integrity," presidential office adviser Mykhailo Podolyak wrote on Twitter on Tuesday evening.

Earlier, the Ukrainian Foreign Ministry issued a statement declaring the organization of the "sham referendums" a criminal offense.

Deputy Prime Minister Iryna Vereshchuk also called on people to ignore the vote, "and thus help the army and themselves."

Anyone applying for a Russian passport – a major tool used by Russia to consolidate its control over the people in territories it has occupied – could face up to 15 years in prison, she said on Ukrainian television.