President Vladimir Putin will begin legally annexing four Ukrainian districts to Russia on Friday, a move that the United Nations has criticized as a “dangerous escalation.”

Moscow’s planned annexation of 15% of Ukraine’s land, following what Kyiv and Western nations claim were phony referendums orchestrated at gunpoint in Russian-held territories, demonstrates that Putin is pressing down on his war despite a huge military setback earlier this month.

Ukrainian army moved to conquer the Russian-held eastern town of Lyman in the Donetsk region on Thursday, marking a new setback for Putin’s campaign even as he prepared to proclaim the territory part of Russia, military analysts said.

“Any decision to proceed with the annexation of the Ukrainian regions of Donetsk, Luhansk, Kherson, and Zaporizhzhia would have no legal value and needs to be denounced,” UN Secretary General Antonio Guterres told reporters.

“Any decision by Russia to go forward will further jeopardize the prospects for peace,” he added.

Ukrainian President Volodymr Zelenskiy announced an emergency meeting with his security and defence chiefs on Friday, and promised a harsh response to a step he says has killed off chances of reviving peace talks.

The votes “are worthless and do not change reality. The territorial integrity of Ukraine will be restored,” he said.

Ukraine’s top general said he and the top U.S. Army commander in Europe had discussed the war and that he had received assurances of further support from Washington.

Putin’s annexation ceremony will be held in one of the Kremlin’s grandest halls with the pro-Russian figures Moscow considers to be leaders of the four Ukrainian regions. Russia says the referendums were genuine and showed public support.

Putin’s spokesman Dmitry Peskov added Putin would deliver a major speech and there would be a concert on Moscow’s Red Square. A tribune has already been set up there with giant video screens and billboards proclaiming “Donetsk, Luhansk, Zaporizhzhia, Kherson – Russia!”

Peskov did not say whether Putin would make an appearance at the concert. He did so at a similar event in 2014 after Russia proclaimed it had annexed Ukraine’s Crimea region.

According to a political adviser to Ukraine’s president, the event “does not make legal sense” and will be a “Kremlin freak show.”

Washington and the European Union are planning new penalties against Russia in response to the annexation proposal, and several of Russia’s closest traditional allies, including as Serbia and Kazakhstan, have stated that they would not recognize the move.

In a speech last week, Putin openly supported the annexation plans while simultaneously announcing the call-up of hundreds of thousands of Russian reservists and threatening to use nuclear weapons to protect Russian territory if necessary.

On Thursday Putin said that the West stood ready to provoke “color revolutions” and a “bloodbath” in any country, without naming a specific country.

With tens of thousands of Russian men fleeing abroad to escape Putin’s military call-up, Finland shut one of the few remaining routes to Europe, saying it would no longer let Russians enter by land with EU tourist visas.

More than half of Russians felt fearful or anxious after hearing of the call-up, according to a poll released by the independent Levada Centre on Thursday.

The head of the upper house of the Russian parliament has said the chamber could consider the incorporation of the four regions on Oct. 4, three days before Putin’s 70th birthday.

What Russia is billing as a celebration comes after Moscow has faced its worst setbacks of the war, with its forces routed in recent weeks in Ukraine’s northeast.

Some military experts say Kyiv is poised to deliver another major defeat, gradually encircling the town of Lyman, Russia’s main remaining bastion in the northern part of Donetsk province. Its fall could open the way for Ukrainian forces to launch attacks on swathes of territory that Russia now aims to annex.

“The position for Russian soldiers in Lyman seems increasingly grave as Ukrainian forces are likely to cut them off,” Carl Bildt, a former Swedish prime minister, stated on Twitter.

“Another humiliating setback for the Russian invading troops looms.”

Kyiv has so far refrained from revealing anything about the situation in Lyman. A day earlier, Russia’s Defense Ministry announced that a Ukrainian onslaught on Lyman had failed, with 70 Ukrainian soldiers killed.