Moscow-held regions of Ukraine will vote on Russia’s annexation in the coming days, separatist officials said Tuesday, while Kiev’s forces retake territory captured by Moscow’s forces.

Separatist authorities in the eastern Donetsk and Lugansk regions and the southern Kherson region said they would hold the vote for five days, from Friday this week to Tuesday.

These areas are at the forefront of a wide-ranging Ukrainian counteroffensive, in which Kiev’s forces have retaken hundreds of towns and villages that have been under Russia’s control for months.

Their integration into Russia would represent a major escalation of the conflict, as Moscow could try to claim it was defending its own territory from Ukrainian forces.

Kyiv said the “sham” votes were meaningless and vowed to “take out” threats posed by Russia, saying its forces would continue to retake territory regardless of what Moscow or its proxies announced.

Denis Miroshnichenko, a separatist leader in the Lugansk region, said pro-Moscow lawmakers voted to hold the September 23-27 vote.

Shortly after, a news portal linked to the separatist authorities in Donetsk said the region would vote on the same dates.

Large swathes of the industrial Donbass region — made up of Donetsk and Lugansk — have been controlled by Moscow-backed separatists since 2014 after nationwide demonstrations toppled a pro-Kremlin Ukrainian president.

Russia then annexed the Black Sea peninsula of Crimea from Ukraine in a vote criticized by Kyiv and the West, which subsequently imposed sanctions.

Authorities in Ukraine’s southern Kherson region also announced on Tuesday that they would vote on the same dates for Russia’s annexation.

“I am sure that the incorporation of the Kherson region into the Russian Federation will secure our territory and restore historical justice,” said Moscow-based head of this region Vladimir Saldo.

He repeated a phrase used earlier in the day by Russia’s former president and prime minister, who cited correcting historical errors, but also said the votes would strengthen Russia’s armed forces.

“Trespassing into Russian territory is a crime and when committed it allows you to use any force possible in self-defense,” Dmitry Medvedev, now deputy chairman of Russia’s Security Council, said on social media.

He said the decisions are binding and no future leader of Russia has the authority to reverse them.

“That is why these referendums are so feared in Kyiv and in the West. Therefore, they must be carried out,” he added.

Pro-Moscow authorities in Ukraine’s Zaporizhzhia region – home to Europe’s largest nuclear power plant – also announced they would vote on joining Russia on the same dates.

The head of the Russian-installed administration in Zaporizhzhia, Yevgeny Balitsky, said on social media that he had signed a decree to vote on the region’s “territorial affiliation”.

The chief of staff of Ukrainian President Volodymyr Zelenskyy, Andriy Yermak, promised a decisive reaction from Kiev to the annexation votes.

“Ukraine will solve the Russian question. The threat can only be eliminated by force,” Yermak said.

Foreign Minister Dmytro Kuleba said the “sham” referendums would change nothing.

“Ukraine has every right to liberate its territories and will continue to liberate them whatever Russia has to say,” he said in an online statement.

The votes come at a crucial time in Russia’s nearly seven-month invasion of Ukraine.

Russia suffered embarrassing battlefield casualties this month as Ukrainian troops retook hundreds of towns and villages from Moscow’s forces.

Political scientist Tatiana Stanovaya wrote on social media that the announcement of the votes was a direct result of the counter-offensive’s success.

Putin, she said, wants to threaten full deployment of the Russian military, including nuclear weapons, to defend Russian territory, including the newly annexed regions.

“Putin does not want to win this war on the battlefield. Putin wants to force Kyiv to surrender without a fight,” she said.

Speaking to newly appointed foreign ambassadors in Moscow on Tuesday, Putin said Russia would continue on its “sovereign course” on the international stage ahead of the UN General Assembly.