Ramzan Kadyrov, the strongman leader of Chechnya, said Monday that he was in Ukraine alongside Russian forces who are leading an offensive in the country.
Kadyrov, who is accused by international NGOs of serious human rights violations in the tightly controled Caucasus republic, posted a video on Telegram of himself in military uniform studying plans around a table with soldiers in a room.
He said in a message that the video had been shot at Hostomel, an airfield near Kyiv captured by Russian forces in the first days of their offensive.
This information could not be independently verified.
"The other day we were about 20 km from you Kyiv Nazis and now we are even closer," Kadyrov wrote.
He called on Ukrainian forces to surrender "or you will be finished."
"We will show you that Russian practice teaches warfare better than foreign theory and the recommendations of military advisers," he added.
Kadyrov, who rules Russia's Chechnya Republic with an iron fist, is a former rebel turned Kremlin ally with a paramilitary force at his command.
At the start of the Russian offensive, images circulated on social networks showing a square in the Chechen capital Grozny filled with soldiers claiming to be on their way to Ukraine.
Kadyrov's forces are accused of numerous abuses in Chechnya.