Former Russian President Dmitry Medvedev on Thursday said all means could be used to defend territories "incorporated" into Russia from Ukraine.

In a post on Telegram, the ally of Russian President Vladimir Putin cited the decisions regarding partial mobilization that say, among other things, that any weapons in the Russian arsenal, including nuclear, can be used for the protection of the regions.

Putin announced on Wednesday a partial military mobilization calling up to 300,000 reservists for probable deployment to Ukraine and underlined that Russia will use all means to defend the country.

"Referendums will be held, and the Donbass republics and other territories will be admitted to Russia," he said, referring to breakaway regions in eastern Ukraine's industrial heartland.

He added that the protection of all the joined territories will be "significantly strengthened" by the Russian armed forces.

"Russia has announced that not only mobilization capabilities can be used for such protection, but also any Russian weapons, including strategic nuclear and weapons based on new principles," wrote Medvedev, who is now the deputy chairperson of Russia's Security Council.

Ukraine's self-declared republics of Luhansk and Donetsk, along with Russian-controlled parts of Zaporizhzhia and Kherson, will hold referendums on joining Russia from Sept. 23-27, a move the international community says is illegal and would not be recognized.