Almost seven months after Russia's invasion of Ukraine, four areas under Moscow's control have announced plans for urgent so-called referendums on joining Russia.
Russia's invasion has stalled in recent months and Ukraine has recaptured swathes of territory in the north-east.
Now Russian-backed officials in the east and south say they want votes on joining Russia starting this week.
Russia annexed Crimea in 2014, after a vote widely condemned as a sham.
The international community has never recognised the annexation, but it has long been clear that Russia intends to rubber-stamp its takeover of other occupied regions in the same way. Ukraine's Foreign Minister Dmytro Kuleba said that "sham 'referendums' will not change anything".
However, annexing more Ukrainian territory would enable the Kremlin to claim Russia itself was coming under attack from Nato weapons.
The deputy head of Russia's Security Council, Dmitry Medvedev, said early on Tuesday that holding votes in the eastern regions of Donetsk and Luhansk - also known as Donbas - would correct "historical justice" and be irreversible: "After the amendments to the constitution of our state, no future leader of Russia, no official, will be able to reverse these decisions."
Soon afterwards the two breakaway Russian-backed authorities in Donetsk and Luhansk said they would stage votes on 23-27 September. They were both recognised as independent by President Vladimir Putin three days before Russian troops invaded Ukraine from north, east and south.
Russian-installed officials in the southern region of Kherson said they would also hold a vote, and a similar declaration came from Russian-occupied areas of Zaporizhzhia. Russian state media claimed people would be able to vote in person or remotely.
For months, Russian-installed authorities have tried to hold self-styled referendums. There was never any hope of a free or fair vote, and the continuing war has made it impractical even to try to annex areas not fully under their control. Ukraine's counter-offensives have made that harder still.
While most of Luhansk has been in Russian hands since July, on Monday the Ukrainian leader in Luhansk announced that the army had recaptured the village of Bilohorivka.