President Volodymyr Zelenskyy said Ukraine is requesting accelerated NATO membership after Russia formally annexed four occupied regions of Ukraine.

"We have already proven our compatibility with (NATO) alliance standards," Zelenskyy claimed in a video posted by the Ukrainian Presidency on social media.

"We are taking a decisive step by signing Ukraine's application for accelerated accession to NATO," he added.

He also said that Kyiv would not negotiate with Russia – which sent troops into Ukraine on Feb. 24 – as long as President Vladimir Putin was in power.

"Ukraine will not hold any negotiations with Russia as long as Putin is the president of the Russian Federation. We will negotiate with the new president," Zelenskyy said.

His remarks come after Putin signed treaties to annex four Moscow-occupied Ukrainian regions – Donetsk, Kherson, Luhansk and Zaporizhzhia – at a grand ceremony in the Kremlin. The U.S. announced "severe" sanctions shortly after Putin's announcement.

The pro-Kremlin leaders of the annexed territories said the regions voted in favor of becoming part of Russia in referendums that Western capitals and international organizations did not recognize.